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Azathioprine, Oral Tablet

Highlights for azathioprine

Highlights for azathioprine

  1. Azathioprine oral tablet is available as brand-name drugs and as a generic drug. Brand names: Imuran, Azasan.
  2. Azathioprine comes in two forms: an oral tablet and an injectable solution.
  3. Azathioprine oral tablet is used to treat rheumatoid arthritis and to keep your immune system from attacking a new kidney after a transplant.
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Important warnings

Important warnings

FDA warning: Cancer risk
  • This drug has a black box warning. This is the most serious warning from the Food and Drug Administration (FDA). A black box warning alerts doctors and patients about drug effects that may be dangerous.
  • Long-term use of azathioprine may increase your risk of developing certain types of cancer, such as lymphoma, leukemia, and skin cancers.

Other warnings

  • Increased infection risk warning: This medication decreases the activity of your immune system. This may increase your risk of infections.
  • Initial treatment effects warning: Azathioprine may lead to a serious reaction that can cause nausea and vomiting, as well as:
    • diarrhea
    • rash
    • fever
    • tiredness
    • muscle aches
    • liver damage
    • dizziness
    • low blood pressure

These effects usually happen within the first few weeks of starting the medication. If your doctor stops your treatment with the drug, your symptoms should go away.

  • Low blood cell counts warning: Azathioprine increases your risk of developing low blood cell counts, such as a low white blood cell count. Having certain genetic problems can also increase your risk of a blood disorder. Your doctor will give you blood tests to monitor for these blood disorders. They may lower your dosage of this drug or stop your treatment with the medication.

About

What is azathioprine?

Azathioprine is a prescription medication. It comes in two forms: an oral tablet and an injectable solution.

Azathioprine oral tablet is available as the brand-name drugs Imuran and Azasan. It’s also available in a generic version. Generic drugs usually cost less than brand-name versions. In some cases, they may not be available in every strength or form as brand-name drugs.

This drug may be used as part of a combination therapy. That means you may need to take it with other drugs.

Why it's used

Azathioprine is used to treat rheumatoid arthritis (RA). It’s also used to keep your immune system from attacking a newly transplanted kidney.

When you receive a kidney transplant, your immune system views the kidney as something that doesn’t belong in your body. This may cause your body to attack the kidney, which can lead to serious health problems or death. Azathioprine is used to stop your immune system from attacking your new kidney.

In RA, your body attacks your joints, which can cause swelling, pain, and loss of function. Azathioprine is used to stop your immune system from attacking your joints.

How it works

Azathioprine works by decreasing the activity of your body’s immune system. For RA, this keeps your immune system from attacking and damaging your joints. For a kidney transplant, the drug keeps your immune system from attacking the newly transplanted kidney.

Azathioprine belongs to a class of drugs called immunosuppressants. A class of drugs is a group of medications that work in a similar way. These drugs are often used to treat similar conditions.

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Side effects

Azathioprine side effects

Azathioprine oral tablet doesn’t cause drowsiness, but it can cause other side effects.

More common side effects

The more common side effects that occur with azathioprine include:

  • low white blood cell counts
  • infections
  • stomach problems, including nausea, diarrhea, and vomiting

Serious side effects

Call your doctor right away if you have serious side effects. Call 911 if your symptoms feel life-threatening or if you think you’re having a medical emergency. Serious side effects and their symptoms can include the following:

  • Gastrointestinal drug hypersensitivity. Symptoms may include:
    • nausea and vomiting
    • diarrhea
    • skin rash
    • fever
    • muscle aches
    • increased liver enzyme levels
    • liver damage
    • dizziness
    • low blood pressure

    These problems usually happen within the first few weeks of starting the medication. If your doctor stops your treatment with this medication, your symptoms should go away.

  • Pancreatitis. Symptoms may include:
    • severe abdominal pain
    • fatty stools
  • Extreme tiredness
  • Excessive weight loss
  • Severe allergic reaction. Symptoms may include:
    • wheezing
    • chest tightness
    • itching
    • swelling of your face, lips, tongue, or throat

Disclaimer: Our goal is to provide you with the most relevant and current information. However, because drugs affect each person differently, we can not guarantee that this information includes all possible side effects. This information is not a substitute for medical advice. Always discuss possible side effects with a healthcare provider who knows your medical history.

Interactions

Azathioprine may interact with other medications

Azathioprine oral tablet can interact with other medications, vitamins, or herbs you may be taking. An interaction is when a substance changes the way a drug works. This can be harmful or prevent the drug from working well.

To help avoid interactions, your doctor should manage all of your medications carefully. Be sure to tell your doctor about all medications, vitamins, or herbs you’re taking. To find out how this drug might interact with something else you’re taking, talk to your doctor or pharmacist.

Examples of drugs that can cause interactions with azathioprine are listed below.

Gout drugs

Taking allopurinol with azathioprine can increase the levels of azathioprine in your body and increase your risk of side effects. Your doctor may lower your dosage of azathioprine if you’re taking allopurinol.

Taking febuxostat with azathioprine can increase the levels of azathioprine in your body and increase your risk of side effects. These medications should not be used together.

Inflammatory bowel disease drugs

Taking drugs called aminosalicylates with azathioprine can increase the levels of azathioprine in your body and increase your risk of bleeding disorders.

Inflammation drugs

These are TNF-modifier drugs. They work to reduce inflammation and immune system response. Taking these drugs with azathioprine can cause an interaction. Examples of these drugs include:

  • adalimumab
  • certolizumab
  • infliximab
  • golimumab

Medication that affects your immune system

Using cotrimoxazole with azathioprine can decrease the amount of white blood cells in your body needed to fight an infection. This increases your risk of infection.

Using this drug with azathioprine can also increase your risk of side effects of both drugs.

Blood pressure drugs

Using drugs called angiotensin-converting enzyme (ACE) inhibitors with azathioprine can increase the levels of azathioprine in your body and increase your risk of blood disorders.

Blood thinning drug

Using warfarin with azathioprine can decrease the levels of warfarin in your body. This would make warfarin less effective for you. Your doctor may closely monitor your levels of warfarin when starting and stopping treatment with azathioprine.

Hepatitis C drug

Using ribavirin with azathioprine can increase the levels of azathioprine in your body and increase your risk of side effects.

Vaccines

Receiving live vaccines while taking azathioprine may increase your risk of negative side effects from the vaccine. Examples of live vaccines include:

  • nasal flu vaccine
  • measles, mumps, rubella vaccine
  • chickenpox (varicella) vaccine

Receiving an inactivated vaccine while taking azathioprine may make the vaccine less effective.

Disclaimer: Our goal is to provide you with the most relevant and current information. However, because drugs interact differently in each person, we can not guarantee that this information includes all possible interactions. This information is not a substitute for medical advice. Always speak with your healthcare provider about possible interactions with all prescription drugs, vitamins, herbs and supplements, and over-the-counter drugs that you are taking.

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Other warnings

Azathioprine warnings

This drug comes with several warnings.

Allergy warning

Azathioprine can cause a severe allergic reaction. Symptoms may include:

  • trouble breathing
  • swelling of your throat or tongue
  • hives

If you develop these symptoms, call 911 or go to the nearest emergency room.

Don’t take this drug again if you’ve ever had an allergic reaction to it. Taking it again could be fatal (cause death).

Warnings for people with certain health conditions

For people with thiopurine S-methyltransferase (TPMT) deficiency: TPMT is an enzyme in your body that breaks down azathioprine. When you don’t have enough TPMT, you’re at increased risk of side effects and blood disorders from azathioprine. Your doctor may do a test to check the levels of TPMT in your body.

For people with low blood cell counts: Azathioprine raises your risk of lowered blood cell counts. Having certain genetic problems can also increase your risk. Your doctor may do blood tests, lower your dosage of azathioprine, or stop your treatment with the medication.

For people with infections: This medication decreases the activity of your immune system. This may make infections that you have even worse.

For people with liver problems: Azathioprine can increase your risk of liver problems, usually in people with kidney transplants. Your doctor will take blood tests to check how well your liver is working. Liver problems usually happen within 6 months of kidney transplant and usually go away when azathioprine is stopped.

Warnings for other groups

For pregnant women: Azathioprine is a category D pregnancy drug. That means two things:

  1. Studies show a risk of adverse effects to the fetus when the mother takes the drug.
  2. This drug should only be used during pregnancy in serious cases where it's needed to treat a dangerous condition in the mother.

Tell your doctor if you’re pregnant or plan to become pregnant. Azathioprine should be used during pregnancy only if the potential benefit justifies the potential risk.

If you become pregnant while taking this drug, call your doctor right away.

For women who are breastfeeding: Azathioprine passes into breast milk and may cause side effects in a child who is breastfed. Breastfeeding isn’t recommended while taking this medication.

For seniors: The safety and effectiveness of azathioprine haven’t been established in people aged 65 years and older.

For children: The safety and effectiveness of azathioprine haven’t been established in people under the age of 18 years.

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Dosage

How to take azathioprine

All possible dosages and forms may not be included here. Your dose, form, and how often you take it will depend on:

  • your age
  • the condition being treated
  • how severe your condition is
  • other medical conditions you have
  • how you react to the first dose

Drug forms and strengths

Generic: Azathioprine

  • Form: oral tablet
  • Strength: 50 mg

Brand: Imuran

  • Form: oral tablet
  • Strength: 50 mg

Brand: Azasan

  • Form: oral tablet
  • Strengths: 75 mg, 100 mg

Dosage for kidney transplant

Adult dosage (ages 18 years and older)

  • Dosage is based on a person’s weight in kilograms (kg).
  • The starting dosage is 3–5 mg per kilogram of body weight taken once on the day of transplant.
  • In certain cases, this dose may be given 1–3 days before the kidney transplant.
  • The maintenance dose is 1–3 mg/kg of body weight per day.

Child dosage (ages 0–17 years)

A safe and effective dose hasn’t been established for this age group.

Dosage for rheumatoid arthritis

Adult dosage (ages 18 years and older)

  • Dosage is based on a person’s weight in kilograms (kg).
  • The starting dosage is 50–100 mg, taken once per day or split into two daily doses.
  • After 6–8 weeks of being on the initial dosage, your doctor may increase your dosage by 0.5 mg/kg of body weight per day.
  • Your doctor may make dosage changes every 4 weeks if needed.
  • The maximum daily dosage is 2.5 mg/kg of body weight per day.
  • For a maintenance dosage, doses can be lowered by 0.5 mg/kg of body weight per day every 4 weeks.

Child dosage (ages 0–17 years)

A safe and effective dose hasn’t been established for this age group.

Special dosage considerations

For people with kidney problems: Your dosage of azathioprine may need to be lowered if you have kidney problems that prevent you from urinating regularly.

For people with TPMT deficiency: Your dosage of azathioprine may need to be lowered if tests show that you have TPMT deficiency. This enzyme helps to break down the drug. Not having enough of the enzyme can lead to an increased risk of side effects from this drug, including bleeding problems.

Disclaimer: Our goal is to provide you with the most relevant and current information. However, because drugs affect each person differently, we can not guarantee that this list includes all possible dosages. This information is not a substitute for medical advice. Always speak with your doctor or pharmacist about dosages that are right for you.

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Take as directed

Take as directed

Azathioprine oral tablet is used for long-term treatment. It comes with serious risks if you don't take it as prescribed.

If you don’t take it at all: If you’re taking it for a kidney transplant, you’re at increased risk of having negative, possibly fatal side effects from your transplant, or having to undergo another kidney transplant.

If you’re taking it for rheumatoid arthritis, your symptoms may not improve or they may get worse over time.

If you stop taking it suddenly: If you’re taking this drug for a kidney transplant, if you stop taking it suddenly, you may experience transplant rejection and kidney failure.

If you’re taking this drug for rheumatoid arthritis, if you stop taking it suddenly, your symptoms of rheumatoid arthritis may come back again.

If you don’t take it on schedule: You may not see a full benefit of this medication. If you double up your dose or take it too close to your next scheduled time, you may be at higher risk of having serious side effects.

What to do if you miss a dose: If you miss a dose, take it as soon as you can. However, if it’s just a few hours until your next dose, skip the missed dose and take the next one only.

Never try to catch up by taking two doses at once. This could result in dangerous side effects.

How to tell if the drug is working: If you’re taking this drug for a kidney transplant, your kidneys should be functioning and you shouldn’t have symptoms of organ rejection. These symptoms can include discomfort or ill feeling, fever, flu-like symptoms, and pain or swelling around the organ. Your doctor will also do blood tests to check for kidney damage.

If you’re taking this drug for rheumatoid arthritis, you should have less swelling and pain in your joints. You should also be able to move around better. These effects should happen after about 12 weeks of being on the medication.

Important considerations

Important considerations for taking azathioprine

Keep these considerations in mind if your doctor prescribes azathioprine for you.

General

  • Take this medication after a meal. This may help lower your risk of stomach problems.

Storage

  • Store this medication at a temperature between 59°F and 77°F (15°C and 25°C).
  • Protect this drug from light.
  • Don’t freeze azathioprine.
  • Don’t store this medication in moist or damp areas, such as bathrooms.

Refills

A prescription for this medication is refillable. You should not need a new prescription for this medication to be refilled. Your doctor will write the number of refills authorized on your prescription.

Travel

When traveling with your medication:

  • Always carry your medication with you. When flying, never put it into a checked bag. Keep it in your carry-on bag.
  • Don’t worry about airport x-ray machines. They can’t harm your medication.
  • You may need to show airport staff the pharmacy label for your medication. Always carry the original prescription-labeled container with you.
  • Don’t put this medication in your car’s glove compartment or leave it in the car. Be sure to avoid doing this when the weather is very hot or very cold.

Clinical monitoring

Your doctor may do certain tests during your treatment with this drug. They may include:

  • Blood tests: Your doctor may do blood tests to check for bleeding disorders once per week during the first month of treatment with this medication. After that, they will do blood tests twice per month for the next two months. If your doctor changes your dosage of azathioprine, they will do blood tests once per month or more often.
  • Liver and kidney tests: Your doctor may do blood tests periodically to check how well your liver and kidneys are working.
  • Test for TPMT deficiency: Your doctor may do a blood test to see if you have TPMT deficiency, because this condition may cause bleeding disorders if you take this drug.

Sun sensitivity

People taking this medication may have a higher risk of skin cancer from too much sun exposure. Wear sunscreen with a high protection factor. Also wear protective clothing, such as a hat and long sleeves.

Availability

Not every pharmacy stocks this drug. When filling your prescription, be sure to call ahead to make sure your pharmacy carries it.

Prior authorization

Many insurance companies require a prior authorization for this drug. This means your doctor will need to get approval from your insurance company before your insurance company will pay for the prescription.

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Alternatives

Are there any alternatives?

There are other drugs available to treat your condition. Some may be better suited for you than others. Talk to your doctor about other drug options that may work for you.

Disclaimer: Healthline has made every effort to make certain that all information is factually correct, comprehensive, and up-to-date. However, this article should not be used as a substitute for the knowledge and expertise of a licensed healthcare professional. You should always consult your doctor or other healthcare professional before taking any medication. The drug information contained here in is subject to change and is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. The absence of warnings or other information for a given drug does not indicate that the drug or drug combination is safe, effective, or appropriate for all patients or all specific uses.

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