Key takeaways

  • Nucala (mepolizumab) can cause side effects that range from mild to serious.
  • More common side effects include headache and back pain.
  • If side effects from Nucala become difficult to tolerate, talk with your doctor.

Specifically, Nucala is a biologic drug prescribed to treat:

Nucala cannot stop an asthma attack. It’s important to contact a doctor right away if you do not see a reduction in asthma symptoms or your symptoms get worse after you start Nucala treatment.

Keep reading to learn about the common, mild, and serious side effects Nucala can cause.

Below are a few of the more common side effects reported by people who used Nucala in studies. These side effects can vary depending on what condition the drug is being used to treat and may not happen to everyone.

More common side effects in people using Nucala for eosinophilic asthma, hypereosinophilic syndrome, and eosinophilic granulomatosis with polyangiitis include:

More common side effects in people using Nucala for chronic rhinosinusitis with nasal polyps include:

More common side effects in people using Nucala for COPD:

  • back pain
  • diarrhea
  • cough

For more information about some of these side effects, see the “Tips for managing side effects” section.

Using Nucala to treat eosinophilic asthma, hypereosinophilic syndrome, and eosinophilic granulomatosis with polyangiitis can cause mild side effects. These include:

Mild side effects have been reported while using Nucala to treat chronic rhinosinusitis with nasal polyps. These include:

Mild side effects have been reported while using Nucala to treat COPD. These include:

  • back pain
  • diarrhea
  • cough
  • mouth or throat pain
  • UTI
  • pain in the arm or leg

For more information about some of these side effects, see the “Tips for managing side effects” section.

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

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

Rare but serious side effects of Nucala have been reported. These include increased risk of serious infection, such as shingles, and anaphylaxis.

If you develop serious side effects with Nucala, 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.

Allergic reaction

For some people, Nucala can cause an allergic reaction. In general, symptoms of an allergic reaction can be mild or serious.

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 keep taking Nucala.

If you have symptoms of a severe allergic reaction, such as swelling or trouble 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 Nucala, they may have you switch to a different treatment.

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

Back pain

Back pain was a common side effect reported in studies of Nucala when used to treat eosinophilic asthma, hypereosinophilic syndrome, eosinophilic granulomatosis with polyangiitis, and COPD. Back pain may include soreness, stiffness, and stabbing or pinching sensations.

Factors that can increase the risk of back pain with Nucala are unknown since studies didn’t look at what was causing it.

What might help

If you have muscle pain during Nucala treatment, consider over-the-counter muscle rubs or patches to help relieve your symptoms. Choose ones with menthol or lidocaine but not aspirin or salicylate, as these can cause asthma to flare up. It’s also best to talk with your doctor. They’ll likely recommend an office visit to discuss treatment options.

Joint pain

Joint pain was a common side effect reported in studies of Nucala when used to treat chronic rhinosinusitis with nasal polyps. Joint pain may cause symptoms such as stiffness, tenderness, swelling, and warmth to the touch.

Factors that can increase the risk of joint pain with Nucala are unknown because studies did not look at what was causing joint pain.

What might help

Elevating a swollen joint or applying a cold pack to the area may help relieve joint pain. But it’s important to talk with your doctor about joint pain from Nucala, especially if your joint is warm to the touch. A warm joint may be caused by an infection. Your doctor will likely recommend an office visit to discuss your symptoms and treatment options.

Here are answers to some commonly asked questions about Nucala’s side effects.

It’s possible. Long-term side effects include those that may start at any time you’re taking a drug, even if you’ve taken it for a long time. It also includes side effects that may not go away, even after you stop taking the drug.

Shingles was reported in all Nucala studies. And shingles may cause long-term effects, such as nerve damage. Because the drug can lower your immune system‘s ability to fight off infections, such as shingles, your doctor may recommend you get a shingles vaccine before starting Nucala. This may decrease your risk of getting shingles, but it won’t eliminate it.

However, a 2019 study on the long-term effects of Nucala for treating asthma showed no additional safety concerns during an average of 3.5 years of treatment.

Talk with your doctor to learn more about possible long-term side effects of Nucala and how to reduce your risk.

No, Nucala does not have a side effect of weight gain. Cancer was not reported in the drug’s studies. If you have questions about cancer with Nucala use, talk with your doctor.

No, Nucala does not have a side effect of weight gain. Weight gain was not reported in the drug’s studies. If you have questions about weight gain with Nucala use, talk with your doctor.

Consider the following important information before starting Nucala.

Nucala can sometimes cause harmful effects in people with certain conditions. This is known as a drug-condition interaction. Other factors may also affect whether Nucala is a good treatment option for you.

Before using Nucala, discuss your health history with your doctor. Nucala may not be right for you if you have certain medical conditions or other factors affecting your health.

Be sure to talk with your doctor if any of the following apply to you:

Nucala cannot stop an asthma attack. It’s a good idea to keep your rescue inhaler with you until you see how Nucala affects your asthma. See a doctor right away if your asthma gets worse or doesn’t improve after you start Nucala.

Nucala may cause a range of side effects, from mild to serious. If you experience bothersome side effects talk with your doctor. Together, you can determine if Nucala is right treatment option to manage your condition.

Disclaimer: While Healthline strives for factual, comprehensive, and current information, this article is not a substitute for a licensed healthcare professional’s expertise. Always consult a doctor before taking or discontinuing any medication. Drug information is subject to change and may not cover all uses, directions, precautions, warnings, interactions, reactions, or adverse effects. The lack of a warning does not guarantee a drug’s safety, effectiveness, or appropriateness for all patients or specific uses. Learn more about our approach to content integrity.