Beetroot Side Effects: Beeturia, GI Effects & Real Cautions

By Erin Rose · Published August 21, 2026 · Reviewed against primary sources · Methodology · About Us

Informational summary of published research — not medical advice. Beetroot is generally well tolerated. If you take blood-pressure medication, a PDE5 inhibitor, or form calcium-oxalate kidney stones, talk to a doctor before regular use.

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Beeturia: the "side effect" most people actually notice

The thing most likely to make you double-take after eating beets or taking a beetroot supplement is beeturia — red or pink discoloration of urine, and sometimes stool. It's caused by betalain, the red pigment in beetroot, surviving digestion in some people instead of being broken down. Classic research on the phenomenon found it happens in about 14% of people, and traced the mechanism: betalain is normally decolorized by stomach acid and colonic bacteria, but oxalic acid protects its red color, and in people who don't fully decolorize it, the pigment is absorbed further down the gut and shows up in urine and stool (Eastwood & Nyhlin 1995, PMID: 7493168).

This is a pigment quirk, not a warning sign. It isn't connected to iron status, kidney function, or the nitrate dose that drives beetroot's actual effects. A 12-week trial giving older adults a full studied dose of standardized beetroot extract (548 mg, 8.8 mmol nitrate/day) documented it in plain terms: participants in the beetroot group reported pink or reddish coloring in their urine and stools, which the researchers described as common after consuming beetroot and not indicative of a health problem — and the trial otherwise concluded beetroot extract was safe and well tolerated over the full 12 weeks (Pinheiro et al. 2024, PMID: 38931296). If you notice it, it's a sign the beets are working their way through you, not that anything is wrong.

Gastrointestinal effects: uncommon, and not the beetroot reputation you might expect

Some individual trials report abdominal pain, diarrhea, nausea, or general digestive discomfort with beetroot juice, particularly at large single doses. But taken as a body of evidence, GI upset is not a defining feature of beetroot the way it is for some other supplements. A systematic review and dose-response meta-analysis pooling 17 randomized controlled trials that reported adverse-event data found that beeturia was the adverse effect most consistently described, that abdominal pain, diarrhea, nausea, and headache were reported in only some individual studies, and that dietary nitrate supplementation did not lead to a statistically significant increase in adverse events compared with placebo (risk ratio 1.00) or in study withdrawals (risk ratio 0.42) (Norouzzadeh et al. 2025, PMID: 40128734). Consistent with that, the 12-week extract trial at the full studied dose reported no gastrointestinal adverse events in the beetroot group at all (Pinheiro 2024, above). If you do notice mild stomach upset, starting at a lower dose or a smaller serving of juice and building up is a reasonable, low-risk adjustment.

The one real medication caution: additive blood-pressure lowering

The practical takeaway: this isn't a hard "don't combine" rule, but it is a "mention it to your doctor" one, especially if you're titrating a blood-pressure medication or regularly using a PDE5 inhibitor. For the full evidence on beetroot's blood-pressure effect, how durable it is, and how this caution fits in, see beetroot for blood pressure.

Oxalate and kidney stones: a caution for a minority, not everyone

Beets are naturally high in oxalate, and dietary oxalate is a recognized contributor to urinary oxalate excretion, the main driver of calcium-oxalate kidney stones, the most common stone type (Massey et al. 1993, PMID: 8335871). This isn't a reason for most people to avoid beetroot — it's a caution specifically for people who form calcium-oxalate stones or have been told by a clinician to watch their oxalate intake. If that's you, discuss regular use of concentrated beetroot juice or extract with your doctor before making it a daily habit. Full detail, including the specific oxalate figures for beet juice, is on the blood-pressure page.

Antibacterial mouthwash: it blunts the benefit, it doesn't cause harm

This isn't a safety caution so much as a "don't waste your dose" one, but it belongs on this page because people ask about it as a side effect. Beetroot's nitrate has to be converted to nitrite by bacteria living on your tongue before it becomes the nitric oxide that does anything — and a strong antiseptic mouthwash disrupts that step. A chlorhexidine-based mouthwash cut oral nitrite production by 90% and reduced plasma nitrite in one trial (Kapil et al. 2013, PMID: 23183324), and a separate trial found the same strong mouthwash blunted the plasma-nitrite rise and blood-pressure response from beetroot juice specifically, while a weaker, non-chlorhexidine rinse had less effect (McDonagh et al. 2015, PMID: 26332900). If you use a strong antibacterial mouthwash daily, especially around when you take beetroot, you're not risking anything — you're just quietly cancelling out the reason you're taking it.

Beetroot side effects at a glance

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Frequently asked questions

Related guides

• Beetroot: what it is & who it's for
• Beetroot Benefits — what the evidence actually shows
• Beetroot for Blood Pressure — the full evidence, durability, and the oxalate/PDE5 safety cautions
• Beetroot Dosage Guide — the ~6–13 mmol nitrate range and a converter
• The Nitrate Label Trap — why the milligram number on the label isn't the dose
• Best Beetroot Supplement — ranked by disclosed nitrate and cost

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