Nucala (mepolizumab) is a brand-name prescription medication. The Food and Drug Administration (FDA) has approved it to treat the following conditions in certain adults and children:

Here are some fast facts about Nucala:

  • Active ingredient: mepolizumab, which is a biologic
  • Drug class: monoclonal antibody
  • How it’s given: subcutaneous injection that’s:
    • given by your doctor or another healthcare professional, or
    • self-administered using a prefilled syringe or autoinjector pen

As with other drugs, Nucala can cause side effects. Read on to learn about potential common, mild, and serious side effects. For a general overview of Nucala, including details about its uses and limitations of use, see this article.

Nucala can cause certain side effects, some of which are more common than others. These side effects may be temporary, lasting a few days to weeks. However, if the side effects last longer than that, bother you, or become severe, be sure to talk with your doctor or pharmacist.

These are just a few of the more common side effects reported by people who took Nucala in clinical trials. These side effects can vary depending on which condition the drug is being used to treat.

More common side effects in people taking Nucala for severe eosinophilic asthma, eosinophilic granulomatosis with polyangiitis, or hypereosinophilic syndrome include:

  • fatigue
  • back pain
  • reaction at the injection site*
  • headache*

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

  • pain in the roof of mouth, tongue, tonsils, or throat
  • joint pain*

* For more information about this side effect, see “Side effect specifics” below.

Mild side effects can occur with Nucala use. These side effects can vary depending on which condition the drug is being used to treat. This list doesn’t include all possible mild side effects of the drug. For more information, you can refer to Nucala’s prescribing information.

Mild side effects in people taking Nucala for severe eosinophilic asthma, eosinophilic granulomatosis with polyangiitis, or hypereosinophilic syndrome include:

Mild side effects that have been reported in people taking Nucala for chronic rhinosinusitis with nasal polyps include:

  • pain in the roof of mouth, tongue, tonsils, or throat
  • upper abdominal pain
  • fever
  • nasal dryness
  • skin rash
  • diarrhea
  • reaction at the injection site*
  • joint pain*
  • mild allergic reaction*

These side effects may be temporary, lasting a few days to weeks. However, if the side effects last longer than that, bother you, or become severe, be sure to talk with your doctor or pharmacist.

Note: After the Food and Drug Administration (FDA) approves a drug, it tracks side effects of the medication. If you develop a side effect while taking Nucala and want to tell the FDA about it, visit MedWatch.

* For more information about this side effect, see “Side effect specifics” below.

Nucala may cause serious side effects. The list below may not include all possible serious side effects of the drug. For more information, you can refer to Nucala’s prescribing information.

If you develop serious side effects while taking 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.

Serious side effects that have been reported and their symptoms include:

For more information about these side effects, see “Side effect specifics” below

Nucala may cause several side effects. Here are some frequently asked questions about the drug’s side effects and their answers.

Is weight gain a side effect of Nucala?

No, weight gain was not reported as a side effect of Nucala.

However, Nucala is sometimes used in combination with oral steroids for people with asthma or nasal polyps. And oral steroid medications, such as prednisone, can cause weight gain, especially if taken long term.

If you are concerned about weight gain during Nucala treatment, talk with your doctor. They can suggest ways to maintain a weight that’s right for you.

Does Nucala cause long-term side effects?

No, Nucala isn’t known to cause long-term side effects. In clinical trials, Nucala did not cause any long-term side effects. However, Nucala is known to cause herpes zoster infection (shingles). With this condition, you may experience long-term symptoms and neurological side effects. For more information, see the “Side effect specifics” section below.

If you have questions about what to expect with Nucala treatment, talk with your doctor. And if you’re concerned about shingles, your doctor may recommend you get the shingles vaccine before starting Nucala treatment. They can discuss with you the benefits of receiving the vaccine.

Could I have hair loss with Nucala?

Hair loss was not reported as a side effect in clinical trials of Nucala. However, Nucala is often used in combination with other drugs, such as rituximab (Rituxan). And these treatments may cause hair loss.

If you have hair loss while receiving Nucala, talk with your doctor. They can help determine what’s causing your hair loss. They can also recommend ways to ease or treat this.

Learn more about some of the side effects that Nucala may cause. To find out how often side effects occurred in clinical trials, see the prescribing information for Nucala.

Reaction at the injection site

Injection-site reactions were commonly reported in clinical trials of Nucala. Injection site reactions are symptoms near the area where you receive an injection. This side effect was reported for each of the conditions Nucala is approved to treat.

Symptoms can include:

  • discoloration or deepening of skin color
  • itchiness
  • pain
  • swelling
  • burning

Injection site reactions are usually mild and go away within a few days.

What you can do

If you’re concerned about this side effect, talk with your doctor before you start Nucala. They can suggest ways to lower the risk of a reaction. They can also recommend ways to relieve the symptoms after an injection.

Joint pain

Joint pain is possible with Nucala treatment. Joint pain was a common but mild side effect reported in clinical trials of Nucala. It occurred in people with chronic rhinosinusitis with nasal polyps. It was not reported as a side effect of Nucala for its other approved uses.

What you can do

If you have joint pain while taking Nucala, talk with your doctor. They can recommend options for relieving your pain. These may include over-the-counter options such as ibuprofen (Advil, Motrin, others).

If your joint pain is not tolerable or doesn’t go away, your doctor may suggest different treatment options for you.

Shingles

Shingles, also known as a herpes zoster infection, is a potential serious side effect of Nucala. Although rare, it was reported in some people with severe eosinophilic asthma who took Nucala. However, it’s not known for sure if Nucala causes shingles.

Shingles is caused by the varicella-zoster virus, which is the same virus that causes chickenpox. People who’ve had chickenpox in the past can also get shingles. This is because after you recover from chickenpox, the virus can still live in your nerve cells for years afterward. However, not everyone who has had chickenpox will develop shingles.

Symptoms can include:

  • painful skin rash and blisters on one side of the body, such as the face or torso
  • muscle aches
  • headaches
  • fever
  • chills

Rarely, shingles can lead to serious neurological complications such as postherpetic neuralgia (long lasting nerve pain in the affected area) and hearing or vision loss.

What you can do

Talk with your doctor about whether you’ve had chickenpox, shingles, or both. Also, tell them if you’ve had the chickenpox or shingles vaccines.

If you haven’t had the shingles vaccine and you are 19 years and older, talk with your doctor. They may recommend you receive the vaccine before starting Nucala treatment. This may decrease your risk of developing shingles while receiving Nucala.

If you have symptoms of shingles before Nucala treatment, tell your doctor. They’ll likely recommend delaying Nucala treatment until your symptoms ease.

If you have symptoms of shingles while receiving Nucala, tell your doctor right away. They can recommend treatments to shorten how long shingles lasts and help ease your symptoms.

Headache

Headache was one of the most common side effects reported for Nucala in clinical trials. This side effect was reported in people receiving Nucala to treat severe eosinophilic asthma, eosinophilic granulomatosis with polyangiitis, and hypereosinophilic syndrome.

What you can do

Talk with your doctor if you’re receiving Nucala and are experiencing headaches that don’t go away or are intolerable. They can recommend over-the-counter options, such as ibuprofen (Advil, Motrin, others), to help relieve this side effect.

Allergic reaction

As with most drugs, Nucala can cause an allergic reaction in some people. This side effect was rarely reported in clinical trials of the drug.

Symptoms can be mild or serious and can include:

  • skin rash
  • itching
  • flushing
  • swelling under your skin, typically in your eyelids, lips, hands, or feet
  • swelling of your mouth, tongue, or throat, which can make it hard to breathe
  • hypotension (low blood pressure)

What you can do

For mild symptoms of an allergic reaction, call your doctor right away. They may recommend ways to ease your symptoms and determine whether you should keep taking Nucala. However, if your symptoms are serious and you think you’re having a medical emergency, immediately call 911 or your local emergency number.

Your doctor will give you your first dose of Nucala in their office or clinic. This is so that they can watch for any signs or symptoms of an allergic reaction after the injection. They may continue giving you each dose in their office. Or they’ll show you how to give yourself Nucala injections at home if they recommend that it’s safe. (To learn more about how Nucala is given, see this article.)

Be sure to talk with your doctor about your health history before you take Nucala. This drug may not be the right treatment for you if you have certain medical conditions or other factors that affect your health. These are considered drug-condition or drug-factor interactions. The conditions and factors to consider include:

Asthma attack. You should not use Nucala during an asthma attack or when your asthma is making breathing difficult. Nucala is not meant to treat asthma attacks. Talk with your doctor about what you should do if you have an asthma attack.

Helminth infections. Tell your doctor if you’ve ever had a helminth infection (parasitic infection caused by worms). If you have a helminth infection, they may recommend treating it before you start receiving Nucala therapy. Talk with your doctor to determine the right time to start Nucala treatment.

Shingles infection. If you haven’t gotten the shingles vaccine, talk with your doctor before starting Nucala treatment. They may recommend that you get the shingles vaccine before receiving Nucala injections. The vaccine may reduce your risk of getting a shingles infection.

Allergic reaction. If you’ve had an allergic reaction to Nucala or any of its ingredients, your doctor will likely not prescribe Nucala. Ask your doctor what other medications may be better options for you.

Alcohol with Nucala

There are no known interactions between Nucala and alcohol.

If you’d like to drink alcohol while receiving Nucala, talk with your doctor. They’ll help determine if this is safe for you.

Pregnancy and breastfeeding while taking Nucala

It’s not known for sure if Nucala is safe to use during pregnancy. In animal studies, Nucala did not cause harm to developing offspring when pregnant animals were exposed to the drug. However, animal studies may not reflect what will happen in humans.

If asthma is not well managed during pregnancy, it could increase certain risks to a developing fetus. These risks include premature birth or a baby with low birth weight.

Talk with your doctor if you’re taking Nucala and considering becoming pregnant or are pregnant. They can discuss with you the risks and benefits of receiving Nucala while you’re pregnant.

If you’re taking Nucala to treat asthma during pregnancy, consider enrolling in a pregnancy registry. Pregnancy registries collect health information about people who receive Nucala during their pregnancy. They also collect information about the health of children born to people who received Nucala while pregnant. This helps other pregnant people make informed decisions about their asthma treatment. You can enroll and provide information about your pregnancy at the registry’s website.

It’s also unknown whether it’s safe to receive Nucala while you’re breastfeeding. There’s not enough information to know whether Nucala passes into breast milk, affects breast milk production, or affects a breastfed child. Talk with your doctor about the risks and benefits of breastfeeding while receiving Nucala.

The common side effects of Nucala are generally mild and go away within a few days. However, serious side effects are possible.

If you’d like to learn more about Nucala, talk with your doctor or pharmacist. They can help answer any questions you have about the drug’s side effects.

Besides talking with your doctor, you can do some research on your own. These articles might help:

  • More information about Nucala. For details about other aspects of Nucala, refer to this article.
  • Cost. If you’d like to learn about Nucala and cost, view this article.
  • A look at asthma. For details about your condition, see our asthma and allergies hub.

Disclaimer: Medical News Today 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.