Tavneos (avacopan) is a prescription drug used to treat a rare condition that causes blood vessel swelling. Tavneos can cause side effects that range from mild to serious. Examples include nausea and diarrhea.

Tavneos is prescribed as part of a treatment for severe active anti-neutrophil cytoplasmic autoantibody (ANCA)-associated vasculitis in adults. Specifically, it’s used to treat two different types of vasculitis: granulomatosis with polyangiitis and microscopic polyangiitis. It’s typically prescribed as part of a treatment plan that includes other medications, such as glucocorticoids.

Tavneos comes as an oral capsule. It contains the active ingredient avacopan.

Keep reading to learn about common, mild, and serious side effects Tavneos can cause. For a general overview of the drug, including details about its uses, see this article.

Some people may experience mild to serious side effects during Tavneos treatment. Examples of the drug’s commonly reported side effects include:

Mild side effects have been reported with Tavneos. These include:

In most cases, these side effects should be temporary. And some may be easily managed. But if you have symptoms that are ongoing or bothersome, talk with your doctor or pharmacist. And do not stop Tavneos treatment unless your doctor recommends it.

Tavneos may cause mild side effects other than those listed above. See the drug’s prescribing information for details.

* To learn more about this side effect, see the “Side effects explained” section.

Serious side effects have been reported with Tavneos. These include:

If you develop serious side effects while taking Tavneos, call your doctor right away. If the side effects seem life threatening or you think you’re having a medical emergency, immediately call 911 or your local emergency number.

* For more information about this side effect, see the “Side effects explained” section.

Note: After the Food and Drug Administration (FDA) approves a drug, it tracks and reviews side effects of the medication. If you’d like to notify the FDA about a side effect you’ve had with Tavneos, visit MedWatch.

Allergic reaction

For some people, Tavneos can cause an allergic reaction. This side effect was reported in studies of the drug.

What might help

If you have mild symptoms of an allergic reaction, such as a mild rash, call your doctor right away. They may suggest a treatment to manage your symptoms and can determine whether you should continue Tavneos treatment.

If you have symptoms of a severe allergic reaction, such as swelling or difficulty breathing, call 911 or your local emergency number right away. These symptoms could be life threatening and require immediate medical care.

If your doctor confirms you’ve had a serious allergic reaction to Tavneos, they may have you switch to a different treatment.

Learn more about some of the side effects Tavneos may cause.

Serious infection

Treatment with Tavneos may increase your risk of developing mild to serious infections. These were commonly reported in the drug’s studies. The two most common serious infections reported were pneumonia and urinary tract infections (UTIs). Symptoms can vary based on the type of infection.

Some symptoms of an infection may include:

What might help

Tell your doctor if you have an infection or symptoms of infection before starting Tavneos. If you do, they’ll likely treat the infection before starting your Tavneos treatment.

If you develop symptoms of an infection while taking Tavneos, tell your doctor right away. They’ll likely do tests to check. If you do have an infection, they’ll probably prescribe a medication to treat it and pause your Tavneos treatment.

If you have questions about your risk of infection with Tavneos, talk with your doctor.

Liver damage

Tavneos can cause liver damage. This was a common side effect reported in the drug’s studies. Liver problems may be mild to serious and even life threatening in rare cases.

Symptoms may include:

  • increase in liver enzymes
  • dark urine
  • nausea and vomiting
  • fatigue
  • upper right abdominal pain
  • bruising or bleeding easily
  • jaundice (yellowing of your skin or the whites of your eyes)

What might help

Before you start Tavneos, your doctor will order a test to check your liver function. They’ll also do this every 4 weeks for the first 6 months of treatment, then periodically for as long as you take Tavneos.

Call your doctor right away if you have symptoms of liver problems. They’ll likely check your liver function. They may pause your Tavneos treatment if you have signs of elevated liver enzymes. In rare cases, if you develop serious liver damage, they may permanently stop your Tavneos treatment.

Talk with your doctor if you have questions about the risk of liver problems with Tavneos.

Hepatitis B virus (HBV) reactivation

If you’ve had hepatitis B, taking Tavneos may cause the virus to become active again. This can happen even if you’ve received treatment for hepatitis B. HBV reactivation was a serious side effect reported in Tavneos studies. It can cause serious liver damage, liver failure, and even death in rare cases.

Symptoms of hepatitis B include:

  • jaundice
  • dark urine
  • fatigue
  • abdominal pain

What might help

Before you start Tavneos treatment, your doctor will test you for HBV. If you have this condition, they may start you on hepatitis B treatment before you begin Tavneos.

Your doctor will monitor you for HBV reactivation during your treatment with Tavneos and for 6 months after it’s finished.

Be sure to tell your doctor if you develop any symptoms of hepatitis B or HBV reactivation. They’ll likely have you stop Tavneos and treat the HBV.

Keeping track of side effects

During your Tavneos treatment, consider taking notes on any side effects you’re having. You can then share this information with your doctor. This is especially helpful when you first start a new drug or combination of treatments.

Your side effect notes can include things such as:

  • what dose of the drug you were taking when you had the side effect
  • how soon you had the side effect after starting that dose
  • what your symptoms were
  • how your symptoms affected your daily activities
  • what other medications you were taking
  • any other information you feel is important

Sharing notes with your doctor will help them learn more about how Tavneos affects you. They can then use this information to adjust your treatment plan if needed.

Tavneos can sometimes cause harmful effects in people with certain conditions. This is known as a drug-condition interaction. Other factors may also affect whether Tavneos is a good treatment option for you. Talk with your doctor about your health history before starting this drug. Be sure to tell them if any of the following factors apply to you:

  • infections
  • liver problems
  • previous allergic reaction to Tavneos
  • history of hepatitis B virus
  • pregnancy
  • breastfeeding

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 another healthcare professional before taking any medication. The drug information contained herein 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.