Tongkat Ali (2026): What the Research Actually Shows
Quick Answer: A 2022 systematic review and meta-analysis of 9 clinical trials (PMID: 36013514) measured hormone levels in men taking tongkat ali. The trials were small and varied a lot, and the authors say more research is needed. It is not a steroid. And standardization matters enormously — a 10% eurycomanone extract lists more eurycomanone per capsule than a 2% extract.
Fadogia agrestis, often sold alongside tongkat ali, has ZERO human clinical trials. Its entire evidence base is three rat studies from one research group. We cover the evidence gap in detail below.
Buying rule: Prefer a declared eurycomanone percentage over an impressive-sounding concentration ratio. The two options below state how much eurycomanone each capsule supplies. The brand cites HPTLC testing for both; we did not find either in a public testing registry.
Standardized tongkat ali picks
200 mg standardized to 2% eurycomanone: 4 mg disclosed eurycomanone per capsule; the brand cites HPTLC testing.
100 mg standardized to 10% eurycomanone: 10 mg disclosed eurycomanone per capsule; the brand also cites HPTLC testing.
As an Amazon Associate we earn from qualifying purchases. These are separated by disclosed potency; neither is ranked from commission.
In-Depth Tongkat Ali Guides
- Best Tongkat Ali Supplement — ranked by eurycomanone standardization, testing, and cost
- Cheapest Tongkat Ali per Dose — priced per serving with the declared eurycomanone shown, and why a 200:1 ratio is not a dose
- Third-Party Tested Tongkat Ali: lot reports and the one registry listing
- Nootropics Depot vs Double Wood — a declared 2% eurycomanone against a 200:1 ratio, and why only one of them is a dose
- Tongkat Ali vs Fadogia Agrestis — one has human evidence, one doesn't
- Tongkat Ali Side Effects — insomnia, and the heavy-metal testing
Comparison Table: Tongkat Ali Products by Cost Per Day
All products ranked by daily cost. Unlike magnesium or vitamin D, there is no single "clinical dose" for tongkat ali — trials have used 200-400mg of varying standardization levels. The key differentiator is eurycomanone content, which we note for each product.
| Product | Dose/Serving | Standardization | Serving Size | Price | Cost/Day | Certification (as labelled) | Buy |
|---|---|---|---|---|---|---|---|
| Nootropics Depot Tongkat Ali 2% Eurycomanone (200mg, 120ct) Best Value | 200 mg | 2% eurycomanone | 1 capsule | $37.98 | $0.32 | Third-Party Tested (HPTLC) | Buy on Amazon |
| Double Wood Tongkat Ali 200:1 Extract (1000mg, 120ct) Budget Pick | 1000 mg | 200:1 ratio (unstandardized) | 2 capsules | $20.95 | $0.35 | Third-Party Tested | Buy on Amazon |
| Nootropics Depot Tongkat Ali 10% Eurycomanone (100mg, 120ct) Quality Pick | 100 mg | 10% eurycomanone | 1 capsule | $77.99 | $0.65 | Third-Party Tested (HPTLC) | Buy on Amazon |
| Momentous Tongkat Ali (400mg, 30 servings) | 400 mg | Root extract (unstandardized) | 2 capsules | $19.99 | $0.67 | Informed Sport Certified | Buy on Amazon |
Note: Unlike vitamins/minerals with standardized RDAs, tongkat ali products vary dramatically in standardization. A 100mg dose of 10% eurycomanone extract delivers more active compound than 1000mg of unstandardized root powder. Cost per day alone does not capture potency differences.
What the Research Looked At
Systematic Review and Meta-Analysis (2022)
Leisegang et al. (2022) is a systematic review and meta-analysis published in Medicina that examined 9 clinical studies on Eurycoma longifolia (PMID: 36013514). Five RCTs were pooled in the meta-analysis.
Key points:
- The trials measured hormone levels in blood, in a mix of healthy volunteers and men with a clinical diagnosis
- Heterogeneity was high (I² = 90.1%), meaning results varied substantially across studies
- Study quality was mixed — several trials lacked proper blinding or used small samples
- The authors say more research is needed before clinical use
Our interpretation: A few small, uneven trials do not support a general recommendation. Treat the results as preliminary.
Stress Markers (Talbott 2013)
Talbott et al. (2013) conducted a randomized, double-blind, placebo-controlled trial in 63 moderately stressed adults (32 men, 31 women) using 200mg/day of standardized tongkat ali extract for 4 weeks (PMID: 23705671). It measured salivary cortisol, other salivary hormone markers and mood scores (Profile of Mood States) against placebo.
Limitations: This was a 4-week study with 63 subjects — a moderate sample size. Results in stressed adults do not tell us what happens in healthy people.
Longer Trial
A 6-month double-blind, placebo-controlled RCT (Leitão et al., 2021) in 45 older men gave 200mg/day of tongkat ali alongside concurrent training (PMID: 33541567). It reported no serious adverse events.
Fadogia Agrestis — The Huberman Effect
Fadogia agrestis became wildly popular after being recommended on the Huberman Lab podcast as a men's-health supplement. Here is the complete evidence base:
Study 1 (2005): Yakubu et al. gave aqueous fadogia stem extract to male rats at 18, 50, and 100 mg/kg for 5 days. Hormone levels changed in a dose-dependent manner (PMID: 16281088). This is the study that launched a supplement industry.
Study 2 (2008): The same group (Yakubu et al.) followed up with a 28-day study at the same doses. At moderate and high doses, the authors reported adverse effects in the rats (PMID: 18023305).
Study 3 (2009): Again the same group found that fadogia extract caused significant changes in liver and kidney enzyme markers at all tested doses over 28 days, with increased serum malondialdehyde (an oxidative stress marker) (PMID: 19755438).
The reality:
- Zero human clinical trials — not one
- All three studies are from the same research group in Nigeria using the same rat model
- The follow-up studies reported adverse effects in the rats, including liver and kidney changes
- No dose-translation studies to establish safe human doses have been conducted
- Rat-to-human dose extrapolation is notoriously unreliable (what works in rats often fails in humans, and what is safe in rats can be dangerous in humans)
Compare this to tongkat ali: 9+ human clinical trials, a systematic review and meta-analysis, EFSA safety evaluation, and studies lasting up to 6 months. The evidence gap is enormous. There are no human trials of fadogia agrestis, so ask a clinician before using it.
What Tongkat Ali Does NOT Do
To be clear about the limitations of the evidence:
- It is not a substitute for medical care. If a doctor has told you to treat a hormone condition, do not replace that treatment with a supplement.
- It is not an anabolic steroid. The studies do not show steroid-like muscle gains. If a supplement company implies otherwise, they are lying.
- It will not work overnight. Studies used 4-week to 6-month courses. Single-dose effects have not been demonstrated.
Product Deep Dives
Nootropics Depot Tongkat Ali 2% Eurycomanone — Best Value
At $0.32/day, this is the most cost-effective standardized tongkat ali available. Each capsule provides 200mg of extract standardized to 2% eurycomanone (4mg eurycomanone per capsule). The brand says it uses HPTLC (High-Performance Thin-Layer Chromatography) testing to verify eurycomanone content; we did not find it in a public testing registry. The 120-capsule bottle lasts 4 months at one capsule per day. This is the product we recommend for most people starting tongkat ali.
Nootropics Depot Tongkat Ali 10% Eurycomanone — Quality Pick
The highest-potency tongkat ali available at $0.65/day. Each capsule delivers 100mg of extract standardized to 10% eurycomanone (10mg eurycomanone per capsule) — 2.5x more active compound per capsule than the 2% version. The brand cites HPTLC testing. The 120-capsule bottle lasts 4 months. Choose this if you have tried the 2% version and want to increase eurycomanone intake without taking multiple capsules, or if you prioritize potency over cost.
Double Wood Tongkat Ali 200:1 Extract — Budget Pick
At $0.35/day, Double Wood offers a 200:1 extract concentration ratio at 1000mg per 2-capsule serving. The caveat: "200:1" is a concentration ratio, not a standardization to eurycomanone content. You do not know how much eurycomanone is in each capsule. The brand says it is third-party tested for purity and contaminants (we did not find it in a public registry), and the lack of eurycomanone standardization makes potency comparison difficult. This is a reasonable budget option if cost is your primary concern, but the Nootropics Depot 2% at $0.32/day is both cheaper and better standardized.
Momentous Tongkat Ali
At $0.67/day for 400mg of Indonesian-sourced root extract, Momentous is confirmed in the Informed Sport registry — making it the only tongkat ali on our list with a registry listing. However, it uses unstandardized root extract (not standardized to eurycomanone content), so actual active compound content is unknown. The Informed Sport certification is its primary value proposition. The 30-serving bottle is the smallest count, making the per-day cost the highest on this list.
How to Choose: Standardization > Dose > Brand
The single most important factor in choosing a tongkat ali supplement is eurycomanone standardization, not total milligrams.
Why standardization matters
Eurycomanone is the primary bioactive quassinoid in tongkat ali, the marker compound the trials standardized to. Raw tongkat ali root contains roughly 0.2-1.5% eurycomanone naturally. Standardized extracts concentrate this:
- 10% eurycomanone — highest potency. 100mg extract = 10mg eurycomanone.
- 2% eurycomanone — good potency. 200mg extract = 4mg eurycomanone.
- "200:1" or "100:1" ratios — these describe concentration ratios, NOT eurycomanone content. A 200:1 extract means 200g of root was used to make 1g of extract, but the actual eurycomanone content is unspecified.
- Raw root powder — lowest and most variable potency. Eurycomanone content unknown.
Decision framework
- Standardization: Choose products with a stated eurycomanone percentage. "200:1" and "100:1" are marketing terms, not standardization.
- Dose: 200-400mg of standardized extract daily, matching clinical trial protocols.
- Third-party testing: Prefer a registry listing; a brand's own HPTLC claim is not the same. Informed Sport if you are a tested athlete.
- Cost per day: After controlling for standardization, compare on daily cost.
Cycling
Some practitioners cycle tongkat ali, but no trial has tested any cycling schedule. The human studies dosed it continuously for weeks to months.
- The longest RCT ran 6 months (PMID: 33541567) with no reported serious adverse events, but data beyond 6 months is scarce
- Tongkat ali may influence hormone signaling, so if you plan to take it for months, talk to your doctor
Take it in the morning or early afternoon — tongkat ali can cause insomnia if taken in the evening.
Safety and Side Effects
What the safety data shows
EFSA (European Food Safety Authority) evaluated tongkat ali root extract and found no genotoxicity or acute toxicity concerns. The 6-month RCT (PMID: 33541567) reported no serious adverse events at 200mg/day.
Reported side effects
- Insomnia — the most commonly reported side effect, especially at higher doses or when taken late in the day. Take in the morning.
- Restlessness / irritability — occasionally reported, may relate to hormonal changes
- Increased body temperature — some users report feeling warmer
- GI discomfort — rare, usually resolves by taking with food
Full breakdown, including who should avoid it and what FDA adverse-event data shows: tongkat ali side effects.
Who should NOT take tongkat ali
- Hormone-sensitive cancers: Prostate cancer, breast cancer, or any condition where hormone modulation is contraindicated
- Pregnant or breastfeeding women: No safety data in these populations
- Children and adolescents: Not studied in developing individuals
- People on TRT or hormonal medications: Potential interactions with hormone therapy. Consult your endocrinologist.
Liver enzyme monitoring
While tongkat ali has not shown hepatotoxicity in clinical trials at standard doses, if you take it long-term, include liver enzymes (ALT, AST) in your regular bloodwork. This is standard precautionary advice for any herbal supplement taken chronically.
Does Tongkat Ali Actually Work? What the Evidence Shows
Ready to buy? See the best tongkat ali picks, ranked by disclosed standardization and testing →
What the research shows, by outcome
The tongkat ali research is small and mixed, and who was studied changes whether the results apply to you at all:
| Outcome | Evidence | The honest read |
|---|---|---|
| Strength / muscle | Mixed | One trial reported some difference in older adults; a separate trial found no effect in young elite athletes. |
| Hormone markers | Mixed | Small trials with different results depending on the group studied. Not a proven treatment for any condition. |
| Product quality | Real problem | Heavy-metal contamination found in a meaningful share of tested products; "200:1" ratio labels don't disclose actual active content. |
If you're going to try it, this is what to buy
Given the two real quality problems above — heavy-metal contamination and vague "extract ratio" labels — the products worth looking at are ones that disclose a specific eurycomanone percentage and say they are independently lab tested.
Nootropics Depot Tongkat Ali 2% Eurycomanone $0.32/day states its standardization on the label; the brand says it is HPTLC-tested, and we did not find that in a public registry. For a more concentrated dose, Nootropics Depot Tongkat Ali 10% Eurycomanone $0.65/day is the same brand at higher potency. Both skip the "200:1 ratio" problem described above.
See every pick in the full tongkat ali buying guide.
Strength and muscle: mixed
For strength and muscle, the picture is mixed. One trial reported some difference in older adults (Henkel 2014, PMID: 23754792). A separate trial found no effect in young elite athletes (Zakaria 2023, PMID: 37398958). Other human trials have measured hormone markers, with mixed results by group; none of this shows that tongkat ali treats any condition.
The quality problems this category has to be honest about
Setting the research questions aside, tongkat ali has two documented problems that have nothing to do with what the herb does in the body:
- Heavy-metal contamination. Tongkat ali root can accumulate heavy metals from soil. Surveys of commercial products have repeatedly found real problems. One analysis found about 36% of products exceeded the mercury limit (Ang 2004, PMID: 15162849). A separate survey found about 26% noncompliant (Ang 2006, PMID: 16567029). Buy only third-party-tested products.
- Undisclosed eurycomanone content. Eurycomanone is the marker compound the trials standardized to. A label that only states a "200:1" or "100:1" extract ratio describes how much root was used to make the extract. It doesn't tell you how much active eurycomanone ended up in it, so the ratio can hide a weak product. A disclosed eurycomanone percentage (2%, 10%) is the meaningful quality marker — compare products on that, not on raw milligrams or extract ratios.
See the full tongkat ali side effects guide for the insomnia data and who should avoid it entirely.
What to keep in mind
- It is not a substitute for medical care. Talk to your doctor about any health concern.
- It is not automatically a quality product just because it's labeled "tongkat ali." Contamination and undisclosed content are real, documented risks — standardization and third-party testing are not optional extras.
How Long Does Tongkat Ali Take to Work?
Ready to buy? See the best tongkat ali picks, ranked by disclosed standardization and testing →
Timeline by Goal
Each row below is a trial's actual duration, not a growth curve. None of these studies checked in earlier and reported a faster result — the duration listed is when the outcome was measured.
| Goal | What the Evidence Shows | Source-Trial Duration |
|---|---|---|
| Talbott 2013 | Placebo-controlled trial in 63 moderately stressed adults on 200mg/day | Measured at trial's end; trial ran 4 weeks total |
| Tambi 2012 | Trial in 76 men on 200mg/day | Measured at trial's end; trial ran 1 month total |
| Leitão 2021 | Placebo-controlled trial in 45 men on 200mg/day | Measured at trial's end; trial ran 6 months total — the longest cited here |
Sources: Talbott SM, et al. J Int Soc Sports Nutr. 2013. PMID 23705671; Tambi MI, et al. Andrologia. 2012. PMID 21671978; Leitão AE, et al. Maturitas. 2021. PMID 33541567.
| Item | Value (weeks) |
|---|---|
| Talbott 2013 | 4 weeks |
| Tambi 2012 | 1 month |
| Leitão 2021 | 6 months |
What to Take While You Wait
Best value Nootropics Depot Tongkat Ali 2% Eurycomanone (200mg, 120ct) $0.32/day
200mg of extract standardized to 2% eurycomanone; the brand says it is HPTLC-tested, and we did not find that in a public registry. That's inside the 200mg dose every trial in the table above used. This is the dose the timeline is based on, not a way to speed it up.
Check price →Higher dose Momentous Tongkat Ali (400mg, 30 servings) $0.67/day
400mg. It is registry-confirmed in the Informed Sport listing. This is the higher end of the studied dose range.
Check price →What Changes the Timeline
- Which outcome was measured. The trials measured different outcomes over 4 weeks, 1 month, and 6 months. These are different questions, not one supplement working at different speeds.
- Who was studied. Results differed by group. A trial in young elite athletes found no effect at all, at any duration (Zakaria 2023, PMID 37398958).
- Dose consistency. All three trials in the table used 200mg/day of standardized extract. None tested whether a higher or lower dose changes the timeline.
Best Time to Take Tongkat Ali: Morning or Night?
As an Amazon Associate we earn from qualifying purchases. Picks are ranked by disclosed standardization, testing, and cost, never commissions.
Quick answer: Take tongkat ali in the morning or early afternoon, not in the evening. Insomnia is its most commonly reported side effect, and it shows up especially at higher doses or when taken late in the day. That's a side-effect-avoidance rule. Take it with or without food, and give it several weeks before judging it, not the same day.
Already know your dose? See the best tongkat ali picks →
What actually decides when to take tongkat ali
| Factor | What to do | Why |
|---|---|---|
| Time of day | Morning or early afternoon | Insomnia is the most commonly reported side effect, especially at higher doses or late in the day |
| With food | Either — with or without food | The dosage guide notes no dietary requirement either way |
Why morning
Take tongkat ali in the morning or early afternoon. The reason is practical: insomnia is the most commonly reported side effect of tongkat ali, especially at higher doses or when taken late in the day, so dosing earlier avoids sleep disruption. That's the sourced reason, and nothing in the trial record ties an hour of the day to any other effect.
With food or on an empty stomach?
Either works. Our tongkat ali dosage guide notes it can be taken with or without food. Some people take it alongside a meal simply because mild GI discomfort is occasionally reported, and food tends to smooth that out — that's a comfort choice, not a dosing requirement.
Give it weeks, not a single dose
No tongkat ali trial measured a same-day effect. The human trials ran weeks to months. The dosage guide suggests giving it 2–4 weeks before judging whether it's doing anything for you — a calendar window, not a clock-time one. Full duration breakdown by outcome: how long tongkat ali takes to work.
Tongkat Ali Side Effects: Insomnia & Mercury Risk
Looking for products, not safety detail? See our tongkat ali comparison, ordered by disclosed standardization and testing information →
Insomnia: the most-reported side effect
Across the human trials behind tongkat ali, insomnia is the side effect that comes up most often, particularly at higher doses or when it is taken later in the day. Reported alongside it, less often, are restlessness or irritability and a feeling of increased body temperature. Mild GI discomfort is reported too, and usually resolves by taking tongkat ali with food.
A 6-month double-blind, placebo-controlled trial reported no serious adverse events at 200mg per day. The simplest way to reduce the insomnia risk is to take tongkat ali in the morning or early afternoon, not in the evening.
Heavy-metal testing: a product-quality topic, not a pharmacology one
Plant roots can take up heavy metals from soil, and published surveys have tested commercial tongkat ali products. One analysis reported about 36% of tested products were above a mercury limit. A separate survey reported about 26% noncompliant. These are category-level survey results, not findings about any one brand, and they are separate from the herb's own pharmacology.
A label that discloses its eurycomanone percentage and says it is independently lab tested gives you more to compare than a vague "200:1 extract ratio," which does not describe active content.
Label testing information
Nootropics Depot Tongkat Ali 2% Eurycomanone $0.32/day states its eurycomanone standardization on the label; the listing says it is HPTLC-tested, and we did not find that in a public registry. Check any product's label for independent lab testing and for a disclosed eurycomanone percentage.
Who should avoid tongkat ali
- Hormone-sensitive cancers (prostate, breast): avoid, since tongkat ali may affect hormone levels.
- Pregnancy and breastfeeding: avoid — there is no safety data in these populations.
- Children and adolescents: not studied in developing individuals.
- On hormonal medication: talk to your endocrinologist first; interactions have not been ruled out.
Long-term data beyond about 6 months is limited, so long-term safety is not known. That is a gap in the research, not evidence of harm.
What FDA adverse-event data shows — and its real limits
FDA adverse-event data (FAERS/CAERS) on tongkat ali is a very small dataset. It logs only 6 total reports naming tongkat ali, of which 4 (66.7%) were coded serious. Reported reactions include Urinary retention, Abdominal pain upper, Chills, Headache, Insomnia, among others — including insomnia, which lines up with what the trials themselves report as the most common complaint.
With only 6 reports on file, this database cannot tell you how common any of these reactions actually is. FAERS/CAERS is a voluntary, spontaneous reporting system with no denominator: no count of how many people took tongkat ali in the same period, and no requirement that anyone file a report at all. A report being filed doesn't mean tongkat ali caused the reaction. A few known limits of this data:
- Reports are voluntary — not all adverse events are reported
- No causal proof — a reported event does not mean the supplement caused it
- High-selling products naturally accumulate more reports (volume bias)
- Brand name matching is fuzzy — some reports may be misattributed or missed
FAERS/CAERS figures via the Verified Supplement Evidence Database, source: FDA CAERS (FAERS for Foods/Supplements).
Tongkat ali side effects at a glance
| Effect | How commonly reported per our sources | What reduces it | When it matters |
|---|---|---|---|
| Insomnia | The most-reported side effect in trials, especially at higher doses or taken late | Take in the morning or early afternoon; consider a lower dose | Always — the default tolerability issue |
| Restlessness / increased body temperature | Reported occasionally | Lower dose; take with food | If noticed, worth mentioning at your next check-up |
| GI discomfort | Rare | Take with food | Minor; usually resolves quickly |
| Heavy-metal (mercury) testing | Published surveys reported roughly a quarter to a third of tested commercial products above limits — a product-quality topic, not an effect of the herb itself | Check labels for third-party testing and a disclosed eurycomanone % | Independent of dose or how you feel |
Common questions
What are the most common tongkat ali side effects?
Insomnia is the side effect reported most often, especially at higher doses or when taken later in the day. Other reports include restlessness, a feeling of increased body temperature, and mild GI discomfort that usually resolves by taking it with food. A 6-month randomized trial reported no serious adverse events at 200mg per day. Taking tongkat ali in the morning is the simplest way to reduce the insomnia risk.
Have tongkat ali products been tested for heavy metals like mercury?
Published surveys have tested commercial tongkat ali root products. This is a product-quality topic, separate from anything the herb itself does. One analysis reported that about 36% of tested products were above a mercury limit, and a separate survey reported about 26% noncompliant. These are category-level survey results, not findings about any one brand. Labels that disclose a eurycomanone percentage and independent testing give you more information to compare.
What does FDA adverse-event data show for tongkat ali?
FDA adverse-event data (FAERS/CAERS) logs only 6 total reports naming tongkat ali, 4 of them coded serious. The small number of reports on file means this data cannot tell you how common any reaction actually is. Reported reactions include urinary retention, abdominal pain upper, chills, headache, among others. FAERS is voluntary with no denominator, so these are raw counts, not a rate, and cannot be compared to other supplements.
Who should avoid tongkat ali or use extra caution?
Avoid tongkat ali if you have a hormone-sensitive condition, such as prostate or breast cancer, since it may affect hormone levels. It has not been studied in pregnancy or breastfeeding, so avoid it there too. If you take hormonal medication, talk to your endocrinologist first, since interactions have not been ruled out. It also has not been studied in children or adolescents.
Verification check · Tongkat Ali
What we could and could not verify about Tongkat Ali
1 of the 4 is confirmed in Informed Sport / Informed Choice: Momentous Tongkat Ali (400mg, 30 servings). The other 3 products we track are not listed in any registry we checked. That means nobody independent has confirmed them; it is not evidence against them.
Method: our Tongkat Ali roster matched against the full public registries of third-party-certified supplements in the US, NSF/ANSI 173, USP Verified and Informed Sport, 5,317 listings, retrieved 2026-08-25. Absence means nobody independent has checked that Tongkat Ali product, not that it failed. Full method and limitations.
Frequently Asked Questions
What does the research on tongkat ali show?
A 2022 meta-analysis of 5 small RCTs (PMID: 36013514) measured hormone levels in men. The trials were few and differed a lot from each other, and the authors say more research is needed before clinical use. Tongkat ali is not a steroid.
How does tongkat ali compare with ashwagandha?
They are different herbs studied for different things. Ashwagandha (KSM-66) has been studied mainly for stress markers such as cortisol. Tongkat ali has been studied mainly for hormone markers in small trials. They have not been compared head to head, and combining them has not been studied.
What is the correct tongkat ali dosage?
Clinical trials used 200-400mg per day of standardized extract. The critical variable is standardization: 100mg of 10% eurycomanone extract delivers 10mg of active compound, while 200mg of 2% extract delivers 4mg. Most trials used 200mg of standardized water-soluble extract, taken with food, in the morning or early afternoon. Cycling is a convention that no trial has tested.
What are tongkat ali side effects?
In the studies at 200-400mg/day, side effects were generally mild. The most common side effect is insomnia, especially at higher doses or when taken later in the day. Other reports include restlessness, increased body temperature, and mild GI discomfort. The 6-month RCT (PMID: 33541567) found no serious adverse events. Take in the morning with food to minimize side effects.
What is known about fadogia agrestis safety?
There is no human safety data. The entire evidence base is three rat studies from one Nigerian research group (2005-2009). The follow-up studies reported adverse effects in the rats at moderate/high doses (PMID: 18023305), including liver and kidney enzyme changes (PMID: 19755438). No human clinical trials have ever been conducted. Ask a clinician before using it. Tongkat ali has been studied in 9+ human trials and reviewed by EFSA.
Is there one timeline for how long tongkat ali takes to work?
No single number. The trials behind this site range from 4 weeks to 6 months, and each measured a different outcome.
How long were the tongkat ali stress trials?
The one trial that measured stress markers ran 4 weeks. In 63 moderately stressed adults, 200mg/day for 4 weeks was compared with placebo on cortisol, other hormone markers and mood scores (Talbott 2013, PMID 23705671). The trial did not report an earlier check-in.
What was the longest tongkat ali trial?
Six months. A placebo-controlled RCT of 200mg/day in 45 older men (Leitão 2021, PMID 33541567) is the longest human trial cited on this site. It reported no serious adverse events.
What time of day should I take tongkat ali?
Morning or early afternoon. Insomnia is tongkat ali's most commonly reported side effect, and it shows up especially at higher doses or when taken late in the day. Taking it earlier in the day is a side-effect-avoidance rule, not a way to boost its hormonal effect.
Does taking tongkat ali in the morning change its effect on cortisol?
No — that link isn't sourced. The trial that measured cortisol and other hormone markers dosed 200mg/day for 4 weeks without tracking what time participants took it. The morning recommendation exists to avoid insomnia, not to optimize a hormonal response.
Should tongkat ali be taken with food or on an empty stomach?
Either. This site's dosage guide notes it can be taken with or without food. Some people take it with a meal simply to reduce mild GI discomfort, which is occasionally reported at higher doses.
Do I need to cycle tongkat ali, taking breaks every few weeks?
Cycling is a practitioner convention, not something the trials tested — the human studies simply dosed it continuously for weeks to months.
Related Comparisons
- Ashwagandha Evidence Review — KSM-66 vs Sensoril and the cortisol research
Sources
- Leisegang K, et al. "Eurycoma longifolia (Jack) Improves Serum Total … in Men: A Systematic Review and Meta-Analysis." Medicina (Kaunas). 2022;58(8). PMID: 36013514
- Talbott SM, Talbott JA, George A, Pugh M. "Effect of Tongkat Ali on stress hormones and psychological mood state in moderately stressed subjects." J Int Soc Sports Nutr. 2013;10(1):28. PMID: 23705671
- Yakubu MT, Akanji MA, Oladiji AT. "Effects of oral administration of aqueous extract of Fadogia agrestis stem on some testicular function indices of male rats." J Ethnopharmacol. 2008;115(2):288-92. PMID: 18023305
- Yakubu MT, et al. "Mode of cellular toxicity of aqueous extract of Fadogia agrestis stem in male rat liver and kidney." Hum Exp Toxicol. 2009;28(8):469-74. PMID: 19755438
- George A, et al. "Tongkat Ali as a potential herbal supplement for physically active male and female seniors — a pilot study." Phytother Res. 2014;28(4):544-50. PMID: 23754792
- Zakaria FH, et al. "Eurycoma longifolia in elite athletes." Biol Sport. 2023. PMID: 37398958
- Ang HH, et al. "Mercury contamination of tongkat ali products." Int J Toxicol. 2004. PMID: 15162849
- Ang HH, Lee KL. "Contamination of mercury in tongkat ali (Eurycoma longifolia) herbal preparations." Food Chem Toxicol. 2006. PMID: 16567029
- Li CH, et al. "Acute and 13-week subchronic toxicity of Eurycoma longifolia." Evid Based Complement Alternat Med. 2013. PMID: 24062779
- FDA CAERS (FAERS for Foods/Supplements) — tongkat ali category summary, via the site's Verified Supplement Evidence Database.