Allopurinol interactions to avoid

Drug interactions | Food interactions | Other interactions | Avoiding interactions | When to see a doctor

Allopurinol, also known as its brand-name counterpart Zyloprim or Lopurin, is approved by the Food and Drug Administration (FDA) for the treatment of gout and recurrent kidney stones. It’s also used to lower uric acid levels in people with certain types of cancer. It belongs to a class of drugs called xanthine oxidase inhibitors, which reduce uric acid levels by blocking a specific protein in the body. 

Although allopurinol is an effective treatment option, it can interact with several medications, such as certain blood pressure medications, diuretics, immunosuppressants, and antibiotics. These interactions can cause side effects or affect how allopurinol works. Additionally, people with kidney disease should use caution when taking allopurinol. Read on to learn more about potential allopurinol interactions and how to minimize the risk of harm.

Allopurinol drug interactions

Allopurinol may interact with several different drugs. The effects of these interactions differ depending on the specific medication.

Certain immunosuppressants

Allopurinol may interact with certain immunosuppressants, including Imuran (azathioprine), Purixan (mercaptopurine), and Neoral (cyclosporine). Immunosuppressants are medications that weaken the immune system. This is necessary in certain situations, such as when someone has an autoimmune disorder (where your immune system attacks your body) or for organ transplant recipients (to keep your immune system from rejecting the new organ).

Taking allopurinol with Imuran (azathioprine), Purixan (mercaptopurine), or Neoral (cyclosporine) can increase the levels of these drugs in the body. This can result in serious adverse effects, including low blood cell counts. Due to this risk, healthcare providers will likely prescribe a lower dosage of these medications. They may also monitor you more closely for side effects.

Angiotensin-converting enzyme (ACE) inhibitors

Taking ACE inhibitors with allopurinol can increase your risk of a hypersensitivity reaction, which is also known as an allergic reaction. Allopurinol may cause serious skin rashes. When taken with other drugs that cause serious skin reactions, such as ACE inhibitors, this risk is compounded. In some instances, this interaction may lead to a serious skin condition called Stevens-Johnson syndrome (SJS). Symptoms of SJS include fever, sore throat, red or purple rash that spreads, blisters on the skin, mouth, nose, eyes, or genitals, and skin shedding. If you develop any symptoms of SJS, get emergency medical help right away.

Examples of ACE inhibitors include:

• Zestril (lisinopril)
• Capoten (captopril)
• Vasotec (enalapril)
• Accupril (quinapril)

Thiazide diuretics

Thiazide diuretics, such as Microzide (hydrochlorothiazide), are medications prescribed for hypertension (high blood pressure) and fluid buildup. Taking thiazide diuretics with allopurinol can increase your risk of side effects of allopurinol. Examples include skin rash, diarrhea, nausea, and gout attacks.

Certain antibiotics

Similar to allopurinol’s interaction with ACE inhibitors, taking certain antibiotics with allopurinol may increase the risk of a skin rash. Examples of antibiotics include Amoxil (amoxicillin), ampicillin, and Augmentin (amoxicillin/clavulanic acid). If you’re taking antibiotics with allopurinol and you develop a skin rash, stop taking allopurinol and contact your doctor. If you develop any signs of a serious skin condition, such as fever, blisters, or shedding, get emergency medical help right away.

Warfarin

Allopurinol can enhance the effects of Coumadin (warfarin), which is a blood thinner that’s prescribed for the treatment and prevention of blood clots. This means taking these medications together can make bleeding more likely. Due to this risk, it’s important to report any signs or symptoms of bleeding to your provider right away. Examples include unexplained bruising, black or bloody stool, and nosebleeds.

If you’re taking allopurinol with warfarin, your healthcare professional will monitor you more closely, and they may need to adjust your warfarin dosage.

Allopurinol food interactions

In some cases, foods may interact with drugs. Fortunately, allopurinol doesn’t have any known interactions with foods. However, certain foods may trigger gout. Examples include red meat, certain kinds of seafood, and high fructose corn syrup.

Keep in mind that allopurinol may be taken with or without food. If it causes stomach upset, you can take it after a meal.

Other allopurinol interactions

Drugs may also interact with other substances, including alcohol or caffeine. Read on to learn more about other substances that may affect allopurinol.

Allopurinol and alcohol

While alcohol doesn’t directly interact with allopurinol, it is considered a common trigger of gout. Alcohol may increase uric acid levels in the blood, which worsens gout. It can also make it harder for the kidneys to clear uric acid from the body. For this reason, your healthcare provider may recommend limiting alcohol if you have gout.

Allopurinol and medical conditions

People with certain medical conditions or health factors should use caution when taking allopurinol. Some conditions include but are not limited to:

• Kidney disease
  • People with kidney disease may not be able to clear allopurinol from their body as easily. This means allopurinol can reach higher levels in the body and increase the risk of side effects. Furthermore, allopurinol may cause kidney problems, which may be especially harmful in people with kidney disease.
• Pregnancy
  • It’s not known if allopurinol is safe to take in people who are pregnant. Animal studies have shown that the drug may be harmful to an unborn baby. However, there haven’t been enough studies done in humans to know how the drug would affect an unborn baby.
• Breastfeeding
  • Allopurinol can pass into breast milk, but it’s not known whether the drug is harmful to a breastfed baby. Discuss the use of allopurinol with your doctor if you’re breastfeeding.
• Children
  • It isn’t known if allopurinol is safe or effective in children with gout or kidney stones. Because of this, the drug typically isn’t prescribed for children unless the child has high uric acid levels due to cancer or certain genetic disorders.

How to minimize allopurinol interactions

Taking allopurinol with certain medications can lead to serious side effects, including a life-threatening skin condition called Stevens-Johnson syndrome. To minimize this risk, be sure to keep an updated list of all medical conditions you have and prescription and over-the-counter medications, vitamins, herbs, and supplements you take. Share this list with the healthcare provider and pharmacist so they can identify any possible interactions.

It’s important to keep an eye out for any warning signs of allopurinol interactions as well. These include new side effects, new or worsening symptoms of your condition, or changes in the drug’s effects. Report any warning signs to your doctor.

When to talk to a healthcare provider about allopurinol interactions

Before starting any new medications, be sure to provide your doctor and pharmacist with a list of your medical conditions, medications, vitamins, herbs, and supplements. While we’ve covered the most common allopurinol interactions in this article, there may be other interactions your provider will identify. Discussing your medical history with your providers will help ensure proper health management and monitoring.