6-Mercaptopurine & Nutrient Depletion
Also searched as Purinethol. What the clinical evidence reports, what it may mean, and what to discuss with your pharmacist.
6-Mercaptopurine has been associated with depletion of NIACIN. This does not mean a deficiency will occur — it means these are worth knowing about and, if you take 6-Mercaptopurine long-term, worth raising with your pharmacist or healthcare provider.
Take more than one medication? Open the checker with 6-Mercaptopurine pre-loaded and add the rest to see overlapping nutrient signals.
Reported nutrient depletions with 6-Mercaptopurine
Each record below is shown as published in our licensed clinical database, with its evidence rating and citations. Expand a section for food sources and talking points.
NIACIN
Moderate DepletionMERCAPTOPURINE (6-MP, Purinethol)
High doses of mercaptopurine can cause pellagra, especially after prolonged therapy (e.g., 250 mg daily for 4 years). It has structural similarities to adenine and interferes with synthesis of nicotinamide adenine dinucleotide.
Niacin is a B vitamin your body uses to produce energy and keep your skin, nerves, and digestive system working properly. Here is what makes 6-mercaptopurine unusual: its chemical shape is close enough to a building block of NAD (a key molecule your cells need to make energy) that it can interfere with how the body manufactures niacin-dependent compounds, rather than simply blocking absorption in the gut. At the doses and durations used for some conditions, this interference can meaningfully reduce niacin activity, and in rare cases involving high, prolonged doses, a deficiency state called pellagra has been reported. If you have been on this medication long-term, it is worth asking your pharmacist or doctor whether your niacin status should be checked.
What Vitamin B3 (niacin) does & food sources
Niacin supports energy metabolism, skin health, and nervous system function.
Common food sources:
- Poultry, beef, and fish
- Peanuts and legumes
- Fortified grains
HelloPharmacist pharmacist-reviewed education — separate from the licensed record above.
What to discuss with your clinician
Deficiency is rare in a typical diet. Discuss with your provider before using niacin as a supplement — at pharmacologic doses it behaves like a medication.
HelloPharmacist pharmacist-reviewed education — separate from the licensed record above.
Supplement considerations
High-dose niacin causes flushing and can affect the liver, blood sugar, and uric acid — it is not a casual supplement.
Do not start or stop medications or supplements without professional guidance — supplements can interact with prescription medications.
HelloPharmacist pharmacist-reviewed education — separate from the licensed record above.
Caution: Treat high-dose niacin as a medication decision, not a nutrition one.
Learn more about this nutrient: Niacin — uses, safety & interactions
References (2)
- Stratigos JD, Katsambas A. Pellagra: a still existing disease. Br J Dermatol 1977;96:99-106. PubMed
- Ludwig GD, White DC. Pellagra induced by 6-mercaptopurine. Clin Res 1960;8:212.
This tool is educational and is not a substitute for professional medical advice. An association is not a diagnosis and does not mean a deficiency will occur. Always talk to your pharmacist or healthcare provider before starting, stopping, or changing any medication or supplement.
Disclaimer: This checker finds which nutrients might be depleted by prescription or over-the-counter medications. Each nutrient depletion issue is rated based on clinical significance. Use your own professional judgment prior to making clinical decisions.© 2026 Therapeutic Research Center Licensed records refresh weekly · last updated July 3, 2026.
More about 6-Mercaptopurine
What drug-induced nutrient depletion means
Some medications can, over time, lower the levels of certain vitamins, minerals, or other nutrients — through reduced absorption, increased loss, or changes in how the body uses them.
Association is not deficiency
An entry here means a depletion has been reported or studied — not that it happens to everyone, or that you are deficient. Dose, duration, diet, and your own health all matter.
Evidence varies by pair
Some drug–nutrient links (like metformin and vitamin B12) are well studied; others rest on limited or preliminary research. Each entry shows the evidence rating from our licensed clinical database.
When to ask about labs
If you take an associated medication long-term, ask your healthcare provider whether monitoring is appropriate for you. Not everyone needs testing — your provider can weigh your dose, duration, and symptoms.
Don't self-supplement blindly
Supplements are not risk-free: some can interact with medications, and some (like potassium or magnesium) can be risky with kidney disease. Talk to your pharmacist before adding anything.
Never stop a medication over this
These medications are prescribed for good reasons, and the benefit usually far outweighs a manageable nutrient consideration. Any change belongs in a conversation with your prescriber.
Food first, usually
For many nutrients, a varied diet covers the gap. Each entry lists common food sources; a supplement is a decision to make with your pharmacist or provider, not a default.
6-Mercaptopurine & nutrients: FAQs
Does 6-Mercaptopurine deplete NIACIN?
Should I take a supplement because I take 6-Mercaptopurine?
Should I stop taking 6-Mercaptopurine?
Where does this information come from?
Questions about 6-Mercaptopurine and your nutrition?
Ask a licensed pharmacist — free, no appointment needed.
Sources & How We Checked
Nutrient depletion records for 6-Mercaptopurine are evidence-graded and sourced from the Natural Medicines database, and are displayed as published with their citations.
- Natural Medicines (Therapeutic Research Center) — Evidence-graded clinical reference for drug-induced nutrient depletions, supplements, and interactions — the basis for this page.
- MedlinePlus, U.S. National Library of Medicine — NIH consumer drug information, used for medication overviews across the site.
Content is written and reviewed by licensed HelloPharmacist pharmacists. See our data sources and editorial standards for how this information is built and checked.