Which Supplements Can You Buy With Your HSA or FSA? (2026 Guide)
Yes — many supplements ARE eligible for HSA/FSA purchase, but most require a Letter of Medical Necessity (LMN) from your doctor for a diagnosed condition. The IRS rule is simple: your supplement must treat a specific medical condition, not just "general wellness."
A few items are always eligible without an LMN — prenatal vitamins, glucosamine, and sunscreen (SPF 15+).
The savings: HSA and FSA accounts use pre-tax dollars, so you save roughly ~30% on every purchase (depending on your tax bracket). A $50/month supplement stack drops to about $35/month.
Always Eligible — No Letter of Medical Necessity Needed
These items are considered medical expenses by default and can be purchased with your HSA or FSA card without any additional documentation:
- Prenatal vitamins — always eligible as a pregnancy-related medical expense
- Glucosamine — recognized for osteoarthritis treatment
- Sunscreen (SPF 15+) — classified as preventive care since the CARES Act
- First aid supplies — bandages, antiseptics, wound care
Eligible WITH a Letter of Medical Necessity
The following supplements become HSA/FSA eligible when your doctor provides an LMN linking them to a diagnosed condition. We've included the ICD-10 codes your doctor will use.
| Supplement | Qualifying Condition | ICD-10 Code | Our Comparison |
|---|---|---|---|
| Vitamin D3 | Diagnosed vitamin D deficiency | E55.9 | Vitamin D comparison |
| Iron supplements | Iron deficiency anemia | D50.9 | Iron comparison |
| Vitamin B12 | B12 deficiency | E53.8 | B12 comparison |
| Calcium + Vitamin D | Osteoporosis prevention | M81.0 | Calcium comparison |
| Magnesium | Diagnosed magnesium deficiency | E61.2 | Magnesium comparison |
| Probiotics | Diagnosed GI condition (IBS, dysbiosis) | K58.9 / K63.8 | Probiotics comparison |
| Omega-3 / Fish oil | Diagnosed hypertriglyceridemia | E78.1 | Omega-3 comparison |
| Folate / Folic acid | Pregnancy or MTHFR mutation | E53.8 | Multivitamin comparison |
| CoQ10 | Statin-induced myopathy | G72.0 | — |
Important: The same supplement bought for "general wellness" is NOT eligible. Vitamin D3 for "bone health" — denied. Vitamin D3 for "diagnosed vitamin D deficiency (E55.9)" — approved. The LMN is what makes the difference.
Letter of Medical Necessity — Template
Bring this template to your doctor's appointment. Most physicians will sign it in under two minutes if you have a documented diagnosis:
To Whom It May Concern:
I am writing to certify that [patient name] has been diagnosed with [condition/ICD-10 code] and that [supplement name] at [dose] is medically necessary to treat this condition.
This supplement is not being recommended for general wellness but for a specific medical diagnosis requiring treatment.
Sincerely,
[Physician name, credentials]
[NPI number]
[Date]
Tips:
- Ask your doctor to include their NPI number — some HSA administrators require it
- Request the LMN to cover 12 months so you don't need a new one each purchase
- Keep a copy — your HSA/FSA administrator may audit purchases and request documentation
- One LMN can cover multiple supplements if they treat the same condition
How Much You Save With HSA/FSA
HSA and FSA accounts use pre-tax dollars. Your savings equal your marginal tax rate:
| Tax Bracket | Monthly Cost (Post-Tax) | Monthly Cost (HSA/FSA) | Monthly Savings | Annual Savings |
|---|---|---|---|---|
| 22% | $50.00 | $39.00 | $11.00 | $132 |
| 24% | $50.00 | $38.00 | $12.00 | $144 |
| 30% (fed + state) | $50.00 | $35.00 | $15.00 | $180 |
| 35% | $50.00 | $32.50 | $17.50 | $210 |
HSA bonus: Unlike FSA accounts, HSA funds roll over year to year and can be invested. HSAs have a triple tax advantage — tax-deductible contributions, tax-free growth, and tax-free withdrawals for medical expenses. This makes HSA the single best tax-advantaged account available.
Where to Buy Supplements With HSA/FSA
- Amazon — accepts HSA/FSA cards on eligible items. Look for the "FSA or HSA eligible" badge. You can add your HSA/FSA card as a payment method and filter by eligibility.
- Thorne.com — accepts HSA/FSA cards directly. Thorne products carry NSF Certified for Sport certification. See our Thorne reviews.
- iHerb.com — accepts HSA/FSA payment on qualifying supplements.
- Truemed.com — generates Letters of Medical Necessity at checkout for participating brands. Useful if you don't want to visit your doctor separately for an LMN.
Pro tip: Even if a retailer doesn't accept your HSA/FSA card directly, you can pay out-of-pocket and submit for reimbursement from your HSA/FSA administrator with your receipt and LMN.
HSA vs FSA: Key Differences for Supplement Buyers
| Feature | HSA | FSA |
|---|---|---|
| Requires high-deductible health plan | Yes | No |
| Funds roll over | Yes — indefinitely | Usually no (use-it-or-lose-it, some plans allow $640 rollover) |
| 2026 contribution limit (individual) | $4,300 | $3,300 |
| Can invest funds | Yes | No |
| Supplement eligibility rules | Same — must treat medical condition or be always-eligible | Same |
Frequently Asked Questions
Do I need a Letter of Medical Necessity to buy supplements with my HSA or FSA?
For most supplements, yes. The IRS requires that HSA/FSA purchases treat a specific medical condition, not general wellness. An LMN from your doctor confirms the supplement is medically necessary. A few items — prenatal vitamins, glucosamine, and sunscreen — are eligible without one.
Which supplements qualify for HSA or FSA without a prescription?
Since the CARES Act (2020), OTC health products no longer require a prescription for HSA/FSA reimbursement. But supplements still need to treat a medical condition. Always-eligible: prenatal vitamins, glucosamine, sunscreen (SPF 15+), first aid. Everything else needs an LMN.
How much do I save buying supplements with HSA or FSA?
Your savings equal your marginal tax rate — typically 22-32% federal plus state income tax. A $50/month supplement stack costs about $35/month with HSA/FSA in a 30% bracket, saving $180/year.
Can I use my HSA or FSA card on Amazon?
Yes. Amazon accepts HSA/FSA debit cards on eligible items. Look for the "FSA or HSA eligible" badge. You can also add your HSA/FSA card as a payment method and filter results by eligibility.
What is the ICD-10 code for vitamin D deficiency?
E55.9 (Vitamin D deficiency, unspecified). Other common codes: iron deficiency anemia (D50.9), B12 deficiency (E53.8), magnesium deficiency (E61.2), hypertriglyceridemia for omega-3 (E78.1), osteoporosis (M81.0).