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Mercaptopurine

Mercaptopurine is a chemotherapy medicine used to treat acute lymphoblastic leukemia (ALL) in adults and children as part of a combination maintenance regimen.

Brand names PurinetholPurixan
Drug class Nucleoside Metabolic Inhibitor
Rx Forms 2
Dr. Brian Staiger, PharmD, BCPS
Reviewed by Last reviewed Jul 10, 2026 Content updated Oct 2, 2026
🧬 Where this information comes from Click to expand

The clinical label records used on this page are FDA-filed Structured Product Labeling (SPL) retrieved through openFDA. We identified 6 clinical label sets within the page’s selected clinical scope after exact ingredient or ingredient-combination matching and applicable route/form matching. Forms, routes, brands, labelers, strengths, and NDC product-record counts are built separately from matching FDA National Drug Code Directory records. The linked DailyMed document is a representative official source for verification, not the page’s only clinical source. View the linked label on DailyMed →

✓No current FDA shortage listed · checked Oct 5, 2026
Mercaptopurine at a glance The quick version — the full detail is in the Patient Information Guide below.
Dr. Brian Staiger, PharmD, BCPS
The Pharmacist’s Take By · Clinical pharmacist · Written

Mercaptopurine is an oral chemotherapy medicine, a purine analog (a mimic of a DNA building block) that stops leukemia cells from dividing, and a mainstay of the maintenance treatment that keeps acute lymphoblastic leukemia (ALL) in remission in children and adults. It has been on the market since about 1953 and is available as a generic. Most people tolerate it reasonably well day to day, though nausea, poor appetite, tiredness and mouth sores are common. The real dangers are bone marrow suppression and liver damage, so keep every blood test and call your care team right away for fever, unusual bleeding or bruising, or yellowing skin or eyes.

Clinical pearls

  • Take it the same way every day, always with food or always without, because food changes how much you absorb.
  • Allopurinol for gout sharply raises mercaptopurine levels, so the mercaptopurine dose must be cut steeply if both are taken.
  • A genetic test for TPMT and NUDT15 enzymes shows whether you break it down slowly and may need much lower doses.
  • Skip live vaccines during treatment, since a suppressed immune system can let the vaccine itself cause an infection.
How we write & review this content — our editorial policy →
How you get itPrescription only
Comes asOral suspension, Tablet
Earliest FDA record1953
Companies listing it with the FDA4
FDA label last updatedJan 30, 2026
FDA’s strongest warning (boxed)None on the label

Patient information guide A plain-language walkthrough of Mercaptopurine, written from its FDA label.

What Mercaptopurine is used for

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Mercaptopurine is a chemotherapy medicine used in the maintenance phase of treatment for acute lymphoblastic leukemia (ALL).

  • Acute lymphoblastic leukemia (ALL): Mercaptopurine tablets (including Purinethol) are indicated for adult and pediatric patients with ALL as part of a combination chemotherapy maintenance regimen.
  • Acute lymphoblastic leukemia (ALL): Mercaptopurine oral suspension carries the same indication and is particularly suitable for patients who cannot swallow tablets.

How Mercaptopurine works

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Mercaptopurine is a purine analog — a synthetic molecule that looks like one of the natural building blocks of DNA. Inside cells, it is converted into active compounds called thioguanine nucleotides (TGNs). When TGNs get incorporated into a cancer cell's DNA or RNA, they trigger cell-cycle arrest (the cell stops dividing) and ultimately cell death. Mercaptopurine and its metabolites also block the cell's ability to build new purines from scratch, further starving rapidly dividing cancer cells of the genetic raw materials they need.

How the body handles mercaptopurine depends in part on two enzymes — TPMT and NUDT15. People with reduced activity in either enzyme break down the drug more slowly, leading to higher drug levels and a greater risk of side effects. Genetic or blood testing can identify these individuals so their dose can be safely adjusted.

Mercaptopurine dosage

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Mercaptopurine is taken once daily by mouth as part of a combination chemotherapy maintenance plan set by your oncology team. It should be taken consistently — always with food or always without food — because food reduces how much the body absorbs.

  • The oral suspension should be shaken vigorously for at least 30 seconds before each dose and measured with the provided oral syringe; discard any remaining suspension 8 weeks after opening.
  • Tablets should only be used by patients who can swallow them whole.
  • If you miss a dose, skip it and continue with your next scheduled dose — never take two doses to make up for a missed one.
  • Your doctor will regularly check your blood counts and may adjust your dose based on how your body responds.

Dosing details from the FDA-approved label

From the Mercaptopurine prescribing information (“Dosage and Administration”). Doses are set by your prescriber for your product, condition, kidney function and age — never change a dose on your own.

  • Recommended starting dosage (oral suspension), as part of a combination chemotherapy maintenance regimen
    • 1.5 mg/kg to 2.5 mg/kg (50 mg/m2 to 75 mg/m2) orally once daily
    • Take consistently with or without food; adjust dose to maintain desirable absolute neutrophil count and for excessive myelosuppression
  • Recommended starting dosage (tablets), as part of a combination chemotherapy maintenance regimen
    • 1.5 mg/kg to 2.5 mg/kg orally once daily
    • A recommended dosage for patients less than 17 kg is not achievable because the only available strength is 50 mg; take consistently with or without food
  • Homozygous TPMT or NUDT15 deficiency
    • Patients typically require 10% or less of the recommended dosage
    • Reduce the recommended starting dosage
  • Heterozygous TPMT and/or NUDT15 deficiency
    • Reduce the dosage based on tolerability
    • Most tolerate the recommended dosage, but some require dose reduction; those heterozygous for both may require more substantial reductions
  • Renal impairment (CLcr less than 50 mL/min)
    • Use the lowest recommended starting dosage or increase the dosing interval to every 36 to 48 hours
    • Interval extension stated in the oral suspension label; adjust dosage to maintain ANC at a desirable level and for adverse reactions
  • Hepatic impairment
    • Use the lowest recommended starting dosage
    • Adjust dosage to maintain ANC at a desirable level and for adverse reactions
  • Concomitant use with allopurinol
    • Reduce the dose of mercaptopurine to one-third to one-quarter of the current dosage
Read the label’s full dosing text

2 DOSAGE AND ADMINISTRATION The recommended starting dosage of MERCAPTOPURINE is 1.5 mg/kg to 2.5 mg/kg (50 mg/m 2 to 75 mg/m 2 ) orally once daily as part of a combination chemotherapy maintenance regimen. Adjust dose to maintain desirable absolute neutrophil count and for excessive myelosuppression. ( 2.1 ) Renal Impairment : Use the lowest recommended starting dose or increase the dosing interval. ( 2.3, 8.6 ) Hepatic Impairment : Use the lowest recommended starting dose. ( 2.3, 8.7 ) 2.1 Recommended Dosage The recommended starting dose of MERCAPTOPURINE is 1.5 mg/kg to 2.5 mg/kg (50 mg/m 2 to 75 mg/m 2 ) orally once daily as part of combination chemotherapy maintenance regimen. Take MERCAPTOPURINE either consistently with or without food [see Clinical Pharmacology (12.3) ]. After initiating MERCAPTOPURINE, monitor complete blood counts (CBC) and adjust the dose to maintain absolute neutrophil count (ANC) at a desirable level and for excessive myelosuppression. Evaluate the bone marrow in patients with prolonged myelosuppression or repeated episodes of myelosuppression to assess leukemia status and marrow cellularity. Evaluate thiopurine S-methyltransferase (TPMT) and nucleotide diphosphatase (NUDT15) status in patients with severe myelosuppression or repeated episodes of myelosuppression [see Dosage and Administration (2.2) ]. If a patient misses a dose, instruct the patient to continue with the next scheduled dose. 2.2 Dosage Modifications in Patients with TPMT and/or NUDT15 Deficiency Consider testing for TPMT and NUDT15 deficiency in patients who experience severe myelosuppression or repeated episodes of myelosuppression [see Warnings and Precautions (5.1) , Clinical Pharmacology (12.5) ]. Homozygous Deficiency in either TPMT or NUDT15 Patients with homozygous deficiency of either enzyme typically require 10% or less of the recommended dosage. Reduce the recommended starting dosage of MERCAPTOPURINE in patients who are known to have homozygous TPMT or NUDT15 deficiency. Heterozygous Deficiency in TPMT and/or NUDT15 Reduce the MERCAPTOPURINE dosage based on tolerability. Most patients with heterozygous TPMT or NUDT15 deficiency tolerate recommended dosage, but some require dose reduction based on adverse reactions. Patients who are heterozygous for both TPMT and NUDT15 may require more substantial dose reductions.

Excerpted — the section continues on the label. Read the full Dosage and Administration section on DailyMed →

Mercaptopurine side effects

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The most common side effects of mercaptopurine involve the blood and digestive system.

Common side effects

  • Low blood cell counts (anemia, low white cells, low platelets)
  • Loss of appetite
  • Nausea and vomiting
  • Diarrhea
  • Feeling generally unwell or fatigued (malaise)
  • Skin rash
  • Mouth sores
  • Less common (under 5%): hives (urticaria), elevated uric acid (hyperuricemia), mouth sores, elevated liver enzymes, increased bilirubin (hyperbilirubinemia), skin darkening (hyperpigmentation), infections, pancreatitis
  • Delayed reactions: liver scarring (hepatic fibrosis), hair loss (alopecia), lung scarring (pulmonary fibrosis), reduced sperm count (oligospermia), secondary cancers

When to get medical help

  • Call your doctor right away if you have unusual bruising or bleeding, signs of infection (fever, chills), or extreme tiredness — these may signal dangerously low blood counts (myelosuppression)
  • Get medical help immediately if you notice yellowing of the skin or eyes (jaundice), dark urine, or severe stomach pain — these can be signs of liver damage (hepatotoxicity)
  • Tell your doctor immediately if you develop a high fever, swollen lymph nodes, or feel very ill — this could be a rare but life-threatening condition called macrophage activation syndrome
  • Tell your prescriber right away if you are pregnant or planning to become pregnant — mercaptopurine can cause serious harm to an unborn baby
  • Contact your doctor if you notice any new or unusual lumps, growths, or signs of a new illness — mercaptopurine may increase the risk of certain cancers over time
  • Children under 6 years old should be watched for signs of low blood sugar (hypoglycemia) such as shakiness, confusion, or sweating

Call your doctor right away if you develop fever, unusual bleeding or bruising, yellowing of the skin or eyes, or feel severely unwell — these can signal dangerous bone marrow suppression or liver damage that need prompt attention.

Mercaptopurine warnings and precautions

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  • Myelosuppression (bone marrow suppression): The most common serious risk. Low blood counts can lead to life-threatening infections, bleeding, and severe anemia. Regular blood count monitoring is essential. Patients with TPMT or NUDT15 enzyme deficiency are at much higher risk and may need significantly lower doses.
  • Liver damage (hepatotoxicity): Mercaptopurine can cause serious liver injury, including fatal liver cell death. Liver function tests are checked frequently during treatment. Report jaundice, dark urine, or abdominal pain immediately.
  • Increased risk of malignancies: Mercaptopurine is mutagenic and may raise the long-term risk of certain cancers, including lymphomas and skin cancers. The risk increases with the degree and duration of immune suppression.
  • Macrophage activation syndrome (MAS): A rare, life-threatening immune reaction. Discontinue mercaptopurine immediately if MAS is suspected.
  • Embryo-fetal toxicity: Can cause miscarriage, stillbirth, and fetal harm. Effective contraception is required during treatment and for 6 months after the last dose for women, and 3 months for men.
  • Immunosuppression: Vaccines may be less effective, and live vaccines can cause infection. Consult your care team before any vaccinations.
  • Phenylketonuria (PKU): The oral suspension contains phenylalanine — patients with PKU must be aware of this.

Mercaptopurine interactions

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Mercaptopurine interacts with several common medicines — always tell your doctor and pharmacist everything you take.

  • Allopurinol (gout medicine): Blocks the enzyme that breaks down mercaptopurine, causing levels to rise sharply — dose must be cut to one-third or one-quarter.
  • Warfarin (blood thinner): Mercaptopurine may reduce warfarin's effectiveness; INR (a clotting measure) needs closer monitoring and warfarin dose may need adjustment.
  • Methotrexate: Increases mercaptopurine exposure in the body, raising the chance of side effects; dose adjustment may be needed, especially at high methotrexate doses.
  • Trimethoprim-sulfamethoxazole (antibiotic): Can worsen bone marrow suppression when combined with mercaptopurine.
  • Aminosalicylates (mesalamine, olsalazine, sulfasalazine): May block the TPMT enzyme, increasing mercaptopurine levels and the risk of low blood counts.
  • Other bone-marrow-suppressing drugs: Combined use raises the risk of dangerously low blood counts — blood counts must be monitored more closely.
  • Other liver-toxic medicines: Combined use increases the risk of liver damage — liver function tests should be checked more frequently.

Interactions listed in the FDA-approved label

From the Mercaptopurine prescribing information (“Drug Interactions”): what the manufacturer studied or reported to the FDA.

  • Allopurinol: Allopurinol can inhibit the first-pass oxidative metabolism of mercaptopurine by xanthine oxidase, which can lead to an increased risk of mercaptopurine adverse reactions. Reduce the dose of mercaptopurine when coadministered with allopurinol.
  • Warfarin: Coadministration with mercaptopurine may decrease the anticoagulant effectiveness of warfarin. Monitor the INR in patients receiving warfarin and adjust the warfarin dosage as appropriate.
  • Myelosuppressive products (including trimethoprim-sulfamethoxazole): Myelosuppression may be increased when mercaptopurine is coadministered with other drugs that cause myelosuppression; enhanced myelosuppression has been noted in some patients receiving trimethoprim-sulfamethoxazole. Monitor the CBC and adjust the dose of mercaptopurine for excessive myelosuppression.
  • Aminosalicylates (e.g., mesalamine, olsalazine, sulfasalazine): Aminosalicylates may inhibit the TPMT enzyme, which may increase the risk of myelosuppression when coadministered with mercaptopurine. Use the lowest possible doses for each drug and monitor more frequently for myelosuppression.
  • Hepatotoxic products: Hepatotoxicity may be increased when mercaptopurine is coadministered with other products that cause hepatotoxicity. Monitor liver tests more frequently in patients receiving mercaptopurine with other hepatotoxic products.
  • Methotrexate: Mercaptopurine exposure increases with concomitant methotrexate use, which may increase the risk of mercaptopurine adverse reactions; the mechanism has not been fully characterized. Mercaptopurine dosage may need adjustment when administered concomitantly with high dose methotrexate.
Read the label’s full interactions text

7 DRUG INTERACTIONS • Allopurinol : Reduce the dose of mercaptopurine when coadministered with allopurinol. ( 2.4 , 7.1 ) • Warfarin : Mercaptopurine may decrease the anticoagulant effect. Monitor INR and adjust warfarin dose as appropriate. ( 7.2 ) 7.1 Allopurinol Allopurinol can inhibit the first-pass oxidative metabolism of mercaptopurine by xanthine oxidase, which can lead to an increased risk of mercaptopurine adverse reactions [see Warnings and Precautions ( 5.1 ), Adverse Reactions ( 6.1 )] . Reduce the dose of mercaptopurine when coadministered with allopurinol [see Dosage and Administration ( 2.4 )] . 7.2 Warfarin The coadministration of mercaptopurine with warfarin may decrease the anticoagulant effectiveness of warfarin. Monitor the international normalized ratio (INR) in patients receiving warfarin and adjust the warfarin dosage as appropriate. 7.3 Myelosuppressive Products Mercaptopurine can cause myelosuppression. Myelosuppression may be increased when mercaptopurine is coadministered with other drugs that cause myelosuppression. Enhanced myelosuppression has been noted in some patients receiving trimethoprim-sulfamethoxazole. Monitor the CBC and adjust the dose of mercaptopurine for excessive myelosuppression [see Dosage and Administration ( 2.1 ), Warnings and Precautions ( 5.1 )] . 7.4 Aminosalicylates Aminosalicylates (e.g., mesalamine, olsalazine or sulfasalazine) may inhibit the TPMT enzyme, which may increase the risk of myelosuppression when coadministered with mercaptopurine. When aminosalicylates and mercaptopurine are coadministered, use the lowest possible doses for each drug and monitor more frequently for myelosuppression [see Warnings and Precautions ( 5.1 )] . 7.5 Hepatotoxic Products Mercaptopurine can cause hepatotoxicity. Hepatotoxicity may be increased when mercaptopurine is coadministered with other products that cause hepatotoxicity.

Excerpted — the section continues on the label. Read the full Drug Interactions section on DailyMed →

Not a complete list. The label covers the interactions the manufacturer studied or reported, and our own interaction database does not cover every medicine either. Bring your full medication list, including vitamins and herbal products, to your pharmacist.

🌿106 supplements and herbs with documented Mercaptopurine interactions, ranked by severity Check Mercaptopurine against a supplement or herb →

Before taking Mercaptopurine

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  • Liver or kidney disease: A lower starting dose or less frequent dosing may be needed — tell your doctor about any liver or kidney problems.
  • TPMT or NUDT15 enzyme deficiency: Genetic or enzyme testing may be recommended, especially if you have severe or repeated episodes of low blood counts — deficiency means you may need a much lower dose.
  • Pregnancy: Mercaptopurine can cause miscarriage and fetal harm. Tell your doctor immediately if you are or could be pregnant. Contraception is required during treatment and for 6 months after the last dose (women) or 3 months (men).
  • Breastfeeding: Do not breastfeed during treatment or for 1 week after the last dose.
  • Fertility: Mercaptopurine may impair fertility in both women and men; discuss this with your doctor before starting treatment.
  • Children under 6 or with low body weight: Monitor for signs of low blood sugar (hypoglycemia) such as shakiness or confusion.
  • Older adults: Start at the lower end of the dosing range; age-related changes in liver, kidney, and heart function can affect how the drug behaves.
  • Vaccines: Avoid live vaccines during treatment; all vaccines may be less effective due to immune suppression.
  • Phenylketonuria (PKU): The oral suspension contains phenylalanine — patients with PKU must factor this in.

Mercaptopurine overdose

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Taking too much mercaptopurine can cause immediate symptoms such as nausea, vomiting, loss of appetite, and diarrhea. Delayed effects — which may appear days later — include severe bone marrow suppression, liver problems, gut inflammation, and mouth sores. If an overdose is suspected, seek emergency medical care right away; if caught immediately, inducing vomiting may be considered. Dialysis is not effective at clearing this drug from the body.

What Mercaptopurine does in the body

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The precise relationship between mercaptopurine blood levels and its effect on leukemia — and the timing of that effect — has not been fully established. What is known is that its active metabolites, thioguanine nucleotides (TGNs), accumulate inside cells and disrupt DNA replication, stopping cancer cells from dividing and triggering cell death. Patients with reduced TPMT or NUDT15 enzyme activity accumulate higher concentrations of TGNs, which increases both the therapeutic effect and the risk of serious bone marrow toxicity.

How your body processes Mercaptopurine

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Mercaptopurine is absorbed quickly after an oral dose, typically reaching peak blood levels within about 45 minutes to 2.5 hours. Food reduces the amount absorbed, which is why consistent timing relative to meals matters. The drug has a short half-life — the time it takes for blood levels to fall by half — of roughly 1 to 1.3 hours, though this varies widely between individuals. It is broken down (inactivated) mainly by two pathways: one involving the enzyme TPMT and another involving xanthine oxidase; the resulting inactive metabolites are then cleared through the urine. Children can show wide variation in how much drug reaches their bloodstream, so monitoring is especially important in pediatric patients.

How to store Mercaptopurine

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Store Mercaptopurine Oral Suspension at 20º to 25ºC (68º to 77ºF) . Store in a dry place.

Written from the FDA-approved label with AI and reviewed by our pharmacy team. How we use AI →

106

Supplements & herbs that interact with Mercaptopurine

106 supplements and herbal products have documented interactions with Mercaptopurine in the licensed clinical database we use. Most are manageable — but your pharmacist should know about everything you take, including vitamins and herbals.

Severity mix
  • Major · 4
  • Moderate · 92
  • Minor · 10
ACTIVATED CHARCOAL Major BEER Major SIBERIAN COCKLEBUR Major WINE Major ACTIVE HEXOSE CORRELATED COMPOUND (AHCC) Moderate ALFALFA Moderate AMERICAN GINSENG Moderate ANDROGRAPHIS Moderate +98 more
Every supplement checked against Mercaptopurine — ranked by severity The full interaction hub: 4 major · 92 moderate · 10 minor · every one linked to its full report. Check Mercaptopurine against your exact supplements

Educational information from a licensed clinical database (Natural Medicines) — see our data sources & update cadence. Not medical advice: an interaction being documented does not mean it will happen to you; do not start or stop medications or supplements without professional guidance.

1

Nutrient depletion considerations

Mercaptopurine has been associated with lower levels of 1 nutrient in the clinical literature. This does not mean a deficiency will occur — it means these may be worth discussing with your pharmacist or healthcare provider, especially with long-term use.

NIACIN Moderate Depletion
See the full Mercaptopurine nutrient depletion report

Educational information from a licensed clinical database (Natural Medicines) — not medical advice. Do not start or stop medications or supplements without professional guidance.

Mercaptopurine: pharmacist answers to common questions

Quick, plain-English answers to the questions patients ask most about Mercaptopurine — the kind of thing our pharmacy team would talk through with you at the counter.

What exactly is mercaptopurine used for?

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Mercaptopurine is a chemotherapy medicine used to help keep acute lymphoblastic leukemia (ALL) — a type of blood cancer — in remission. It's used during the maintenance phase of treatment, which means it's taken for an extended period after more intensive chemotherapy to stop the leukemia from coming back. It's always given as part of a combination plan with other medicines, not on its own.

Should I take this with food or on an empty stomach?

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Either is fine, but you need to be consistent. Food reduces how much of the medicine your body absorbs, so if you always take it with a meal or always take it without food, your dose stays predictable. Pick whichever fits your routine best and stick with it every day. Your doctor will adjust your dose based on your blood counts, so consistency helps them do that accurately.

What side effects should I actually watch out for?

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The most common issue is low blood counts — that means you might be more prone to infections, feel tired from low red blood cells (anemia), or bruise or bleed more easily. Nausea, vomiting, loss of appetite, and diarrhea are also fairly common, especially early on. The things to call your doctor about right away are fever (which can signal a serious infection), unusual bleeding, or yellowing of your skin or eyes — that last one can be a sign of liver problems, which is a serious risk with this medicine.

I've heard something about a genetic test related to this drug — what is that about?

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Some people have naturally lower activity of two enzymes — called TPMT and NUDT15 — that help break down mercaptopurine. If those enzymes aren't working well, the drug builds up to higher levels in your body, which raises the risk of severe bone marrow problems. Your doctor may test your blood or your genes to check these enzyme levels, especially if you have repeated episodes of very low blood counts. If the test shows reduced enzyme activity, your dose will be adjusted to keep you safe.

Can I take allopurinol for gout while I'm on mercaptopurine?

▾
This is a very important combination to flag. Allopurinol blocks one of the main pathways your body uses to break down mercaptopurine, so taking both together can cause mercaptopurine levels to rise to dangerous levels. If you do need both medicines, your mercaptopurine dose must be cut to about one-quarter to one-third of the usual amount. Never start or stop allopurinol without telling your oncology team first.

Is it safe to try to get pregnant while taking this medicine?

▾
No — mercaptopurine can seriously harm a developing baby, including increasing the risk of miscarriage and stillbirth. If you're a woman of childbearing age, you need to use reliable contraception throughout your treatment and for 6 months after your last dose. If you're a man, contraception is recommended during treatment and for 3 months after the last dose. If you're already pregnant or think you might be, tell your doctor right away so you can discuss your options together.

Is Mercaptopurine available over the counter?

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No. Mercaptopurine is a prescription medicine: every Mercaptopurine product listed with the FDA is prescription only, so it is not sold over the counter. Your prescriber decides whether it is appropriate for you, and your pharmacist dispenses it.

When was Mercaptopurine first available?

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The earliest FDA record we hold for Mercaptopurine is from 1953: its first approval in Drugs@FDA or its earliest product listing in the NDC Directory, whichever is older. Many older medicines were in use before their first formal FDA approval, so this is the earliest date on record, not necessarily when Mercaptopurine was first used.

Who makes Mercaptopurine?

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4 companies currently list Mercaptopurine products in the FDA's NDC Directory, including Hikma Pharmaceuticals USA Inc., Florida Pharmaceutical Products, LLC, Golden State Medical Supply, Inc.. That count includes repackagers and distributors as well as manufacturers (companies that sell only the raw ingredient are not counted), so fewer companies actually make it; the label on your bottle names the one that supplied yours.

Answers drafted from the FDA-approved label with AI and reviewed by our pharmacy team. How we use AI →

More about Mercaptopurine on HelloPharmacist

📊Mercaptopurine supplement interactions106 checked — ranked by severity 🌿Drug & Supplement CheckerMercaptopurine vs. vitamins & herbs 💬Ask a PharmacistFree answer, usually < 24h 🔎NDC & pricing lookupFind Mercaptopurine NDCs & costs 🅰️Browse Drugs A–ZLook up any medication
Detailed data & references for Mercaptopurine Forms & strengths, pricing, billing codes, manufacturers, safety reports and sourcing — the data behind the page. Most people can stop here. Each section below opens on a tap.

Mercaptopurine forms and strengths (how it comes)

Mercaptopurine is available in 2 forms. Different forms and brands can have different approved uses, doses, schedules, and directions. Follow the instructions for your exact product, and do not switch forms without guidance from your prescriber or pharmacist.

Oral suspension

By mouth
How this form is used
What it may be used for
  • Mercaptopurine oral suspension is used to treat acute lymphoblastic leukemia (ALL) in patients as part of a combination chemotherapy maintenance regimen
Important instructions
  • Mercaptopurine oral suspension should be taken once daily by mouth, consistently either always with food or always without food
  • Shake the Mercaptopurine oral suspension bottle vigorously for at least 30 seconds before each use to make sure it is well mixed
  • Mercaptopurine oral suspension is supplied with two oral dosing syringes (1 mL and 5 mL) — use only the syringe specified for your dose; wash, rinse and dry the syringe after each use
  • Discard any remaining Mercaptopurine oral suspension 8 weeks after opening; this product is a hazardous drug — follow safe handling and disposal instructions provided by your care team
Available strengths 1 strength
20 mg/mL
5 FDA-listed product records ⓘ

Tablet

By mouth
Brands Purinethol
How this form is used
What it may be used for
  • Mercaptopurine tablets and Purinethol are used to treat acute lymphoblastic leukemia (ALL) in adult and pediatric patients as part of a combination chemotherapy maintenance regimen
Important instructions
  • Mercaptopurine tablets and Purinethol are taken once daily by mouth, consistently either always with food or always without food
  • Do not give Mercaptopurine tablets or Purinethol to patients who are unable to swallow tablets
  • If a dose is missed, skip it and take the next scheduled dose — do not take a double dose
  • Mercaptopurine tablets are a cytotoxic (cell-killing) drug — follow all special handling and disposal instructions from your pharmacist or care team
Available strengths 1 strength
50 mg
4 FDA-listed product records ⓘ

Mercaptopurine on the U.S. market: products, makers and brands

How Mercaptopurine appears in the FDA’s National Drug Code Directory — including its dosage forms, strengths, brand names, manufacturers, and FDA-listed product records. These are directory records, not sales or prescription volume.

4 companies list 6 Mercaptopurine product records with the FDA, mostly as oral suspension, tablet; the earliest marketing or approval year on record is 1953. Brand names on the directory include Purinethol, Purixan; the rest are generics.

2
Dose forms ⓘ
4
Labelers (makers, repackagers, distributors)
1
Brand names
6
FDA-listed product records ⓘ
1953
Earliest FDA record ⓘ

FDA-listed product records by dose form (tablet variants merged) — FDA National Drug Code Directory. Record counts are not sales or prescription volume.

Also listed with the FDA, not a patient dose form: Powder (4) — bulk drug substance sold to compounders/manufacturers and multi-item kits. These aren’t counted in the dose-form total above.

Hikma Pharmaceuticals USA Inc.50%
Florida Pharmaceutical Products, LLC17%
Golden State Medical Supply, Inc.17%
Nova Laboratories, Ltd17%

Share of FDA-listed product records by manufacturer — FDA National Drug Code Directory. Record counts are not sales or prescription volume.

How widely Mercaptopurine is used (Medicaid data)

A general measure of how commonly Mercaptopurine is prescribed, based on Medicaid — one of the largest public drug programs. The figure below is prescriptions filled in Q1–Q4 2025, summed across every form and brand of the drug.

Think of this as a proxy for how widely Mercaptopurine is used, drawn from freely available public data. Medicaid is just one program — these numbers don’t include Medicare, other government coverage, or commercial and cash-pay prescriptions, so real-world use is higher than what’s shown here.

23,610
Medicaid prescriptions filled (Q1–Q4 2025)
$5M gross Medicaid reimbursement (before mandatory rebates — net cost is lower)

How commonly is Mercaptopurine prescribed? Of the 1,601 medications we measure, Mercaptopurine ranks #775 by Medicaid prescriptions — more than 52% of them.

Where Mercaptopurine ranks among the drugs we measure · Q1–Q4 2025 · neighbors ±5
Total prescriptions — #775 of 1,601
#770 Dapsone Topical 24,570 Rx #771 Atovaquone 24,509 Rx #772 Spironolactone and Hyd... 24,202 Rx #773 Metaxalone 23,917 Rx #774 Felbamate 23,708 Rx #775 Mercaptopurine 23,610 Rx #776 Nivolumab Injection 23,499 Rx #777 Fosfomycin 23,298 Rx #778 Valganciclovir 23,219 Rx #779 Cetirizine / Pseudoeph... 22,875 Rx #780 Levetiracetam Injectio... 22,631 Rx

Utilization by Mercaptopurine product

Pick a product to see its own Medicaid numbers. Each chip is one clinical product — a specific strength & dosage form as defined by RxNorm — with brand-name and generic versions combined.

The 50 mg oral tablet is the most-dispensed Mercaptopurine product — about 86% of these Medicaid prescriptions.

mercaptopurine 50 MG Oral Tablet Most dispensed

20,380 Medicaid prescriptions (Q1–Q4 2025) 86% of Mercaptopurine prescriptions shown $1.2M gross reimbursement (before rebates) ≈ $58 per prescription (gross)

Summed across the 3 of 10 listed NDC products with Medicaid activity — every brand and generic of this exact strength & form. RxNorm 197931

mercaptopurine 20 MG/ML Oral Suspension

3,230 Medicaid prescriptions (Q1–Q4 2025) 14% of Mercaptopurine prescriptions shown $3.8M gross reimbursement (before rebates) ≈ $1,189 per prescription (gross)

Summed across the 3 of 6 listed NDC products with Medicaid activity — every brand and generic of this exact strength & form. RxNorm 1536484

Shares are of the Medicaid prescriptions shown here. Product grouping follows RxNorm (the National Library of Medicine’s drug terminology), so “one product” means one strength & dosage form regardless of manufacturer. Dollar figures are gross Medicaid reimbursement before mandatory rebates — rebates (often large, especially for brand-name drugs) are confidential, so actual net cost to Medicaid is lower than shown.

Source: Medicaid State Drug Utilization Data (CMS), aggregated by generic ingredient — summed across every NDC (all brands, strengths, salt forms and dosage forms) of Mercaptopurine, and across all states and both fee-for-service and managed-care claims. A general popularity signal; it excludes Medicare, commercial insurance and cash prescriptions, so it is not total U.S. use. Based on the 6 of 16 listed Mercaptopurine NDCs with Medicaid activity.

Compare Mercaptopurine products

A representative set of FDA-listed product records for Mercaptopurine — across manufacturers, strengths, and dosage forms, grouped by form with each product’s manufacturer and how the FDA approved it. The same medicine may be made and packaged by different companies, so a single drug can have many directory entries. (It’s also why a refill can look different — a new shape, color, or box — even though it contains the same medication.)

Strength Route Manufacturer / Labeler Category ⓘ Details
💊Oral suspension
20 mg/mL Oral Hikma Pharmaceuticals USA Inc. × 2 listings ANDA View NDC →
20 mg/mL Oral Nova Laboratories, Ltd NDA AUTHORIZED GENERIC View NDC →
💊Tablet
50 mg Oral Florida Pharmaceutical Products, LLC NDA View NDC →
50 mg Oral Golden State Medical Supply, Inc. ANDA View NDC →
50 mg Oral Hikma Pharmaceuticals USA Inc. ANDA View NDC →

Showing 6 of 6 products — FDA National Drug Code Directory. See every product, package size and price: browse all 6 Mercaptopurine NDCs →

Mercaptopurine recall history

A recall is when a specific batch of a medicine is pulled from the market — usually a manufacturing issue, not a problem with the drug itself. Class I is most serious, Class III least.

The FDA’s enforcement reports list no Mercaptopurine recalls since July 2021.

✅No Mercaptopurine recalls on record since July 2021

Source: FDA enforcement (recall) reports, via openFDA; our copy was last updated Sep 24, 2026.

RxNorm Concept Web — From Ingredient to Every Form and Strength

This page starts with one ingredient concept (IN). The branches below show its dose-form concepts (SCDF), then the available clinical drug and strength concepts (SCD). Combination products remain separate concepts with their own pages.

Ingredient (IN) Mercaptopurine RxCUI 103 2 dose forms · 2 strengths
  1. Dose form (SCDF) Oral Suspension RxCUI 1536483 In current FDA listings
    Clinical drug / strength (SCD) 20 MG/ML RxCUI 1536484
  2. Dose form (SCDF) Oral Tablet RxCUI 372782 In current FDA listings
    Clinical drug / strength (SCD) 50 MG RxCUI 197931

Look up RxCUI 103 in the RxCUI Atlas →

RxNorm is the U.S. National Library of Medicine’s normalized drug vocabulary. Its concept hierarchy can include forms that are not currently marketed; the status on each branch compares that concept with current FDA listings. RxCUIs identify vocabulary concepts, not individual packages or manufacturers.

💵 What Mercaptopurine costs pharmacies (NADAC benchmark)

The national average invoice price pharmacies pay for the drug itself, from CMS's NADAC survey (data as of Sep 30, 2026). This is a supply-cost benchmark — not a retail price and not what you'd pay at the counter.

FormStrengthPharmacy acquisition benchmark
Tablet · Oral 50 mg $1.07 per tablet NDC details & price history
Why show this? Your out-of-pocket cost depends on insurance, pharmacy markup, and discounts — but the acquisition benchmark tells you whether the medication itself is inexpensive or costly, which strengths cost more per dose, and whether a cash-price quote is in a reasonable range. Each row links to the NDC-level record with its full price history.

Source: CMS National Average Drug Acquisition Cost (NADAC), a survey of retail pharmacy invoice prices. Benchmarks shown are the range across package sizes of a representative product for each form and strength — other manufacturers' products may differ.

Mercaptopurine brand names

Mercaptopurine is sold under 2 brand names in the FDA directory — Purinethol, Purixan. A brand and its generic contain the same active ingredient; the brand name belongs to one company's product.

Purinethol Purixan

Who makes Mercaptopurine: manufacturers and labelers

4 companies list Mercaptopurine products with the FDA. By number of product records, the largest are Hikma Pharmaceuticals USA Inc., Florida Pharmaceutical Products, LLC, Golden State Medical Supply, Inc.. Labelers include manufacturers and repackagers; the product in your bottle depends on which one your pharmacy stocks.

Hikma Pharmaceuticals USA Inc. 3 Florida Pharmaceutical Products, LLC 1 Golden State Medical Supply, Inc. 1 Nova Laboratories, Ltd 1

Mercaptopurine drug class (RxNorm)

Mercaptopurine belongs to the Nucleoside Metabolic Inhibitor class.

Pharmacologic class Nucleoside Metabolic Inhibitor
Drug family (ATC) Purine analogues
How it works Nucleic Acid Synthesis Inhibitors

Classified by RxNorm RxClass — the U.S. National Library of Medicine's standardized drug-classification service (Established Pharmacologic Class from the FDA, the ATC drug family from the WHO, and mechanism of action). Reference only, not medical advice.

Sources for this Mercaptopurine page

Core label, product, RxNorm, safety, and utilization data on this page come from the sources identified below. AI-written, editorial, and licensed sections are labeled separately.

📄
FDA-filed drug labels (SPL) Uses, dosing, warnings & side effects from SPL records retrieved through openFDA; the linked representative set can be verified on DailyMed. ✓ Linked label effective Jan 30, 2026
🏭
Forms, brands & labelersAggregated from ingredient-matched FDA National Drug Code Directory product records for Mercaptopurine.
📈
Real-world reportsThe FDA Adverse Event Reporting System (FAERS), served through openFDA.
🚨
Recalls & shortagesopenFDA drug-enforcement reports and the FDA drug-shortage database.
🧾 Clinical label set — FDA-filed SPL labels retained for Mercaptopurine after exact ingredient or ingredient-combination matching and applicable route/form matching
Clinical labels in scope
6
Finished products in the current FDA directory
6
Companies listing them (makers, repackagers, distributors)
4
FDA labeler codes behind them ⓘ
4
Linked representative label ⓘ
Florida Pharmaceutical Products, LLC
Linked label effective
Jan 30, 2026
Composite sections available
22
Linked SPL Set ID
e7309808-5ae8-4a55-90e3-3992ace0da62
Linked SPL Document ID
e7309808-5ae8-4a55-90e3-3992ace0da62
Open the linked representative label on DailyMed ↗

How this page is built

HelloPharmacist combines public FDA and NLM records and does not author the underlying clinical facts. The plain-language sections are written with AI from the FDA-approved label text and reviewed by our pharmacy team before publication. Florida Pharmaceutical Products, LLC is the representative DailyMed label linked for verification and dates. This is general education, not medical advice: always talk to your doctor or pharmacist about your own medicines. How we build and review drug pages →