Benlysta (belimumab) is a prescription drug that’s used to treat certain types of lupus. Benlysta can cause side effects that range from mild to serious. Examples include depression, nausea, and diarrhea.

Benlysta is used in adults and certain children to treat:

Benlysta is a biologic drug, which means it’s made from parts of living cells. The active ingredient in Benlysta is belimumab. (An active ingredient is what makes a drug work.)

The drug comes in two forms:

  • Liquid solution inside prefilled syringes or autoinjectors. This form is given as an injection under the skin.
  • Powder that’s mixed into a liquid solution. This form is given as an intravenous (IV) infusion (an injection given into a vein over a period of time).

Keep reading to learn about the common, mild, and serious side effects that Benlysta 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 their Benlysta treatment.

Examples of Benlysta’s commonly reported side effects include:

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

Mild side effects have been reported with Benlysta. Examples of these side effects include:

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

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

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

Usually, serious side effects with Benlysta are rare. However, serious side effects have been reported with the drug. These include:

If you develop serious side effects during Benlysta treatment, 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.

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 Benlysta, visit MedWatch.

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

Help is out there

If you or someone you know is in crisis and considering suicide or self-harm, please seek support:

If you’re calling on behalf of someone else, stay with them until help arrives. You may remove weapons or substances that can cause harm if you can do so safely.

If you are not in the same household, stay on the phone with them until help arrives.

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Get answers to some frequently asked questions about Benlysta’s side effects.

Is weight gain a side effect of Benlysta?

No, Benlysta shouldn’t cause weight gain. This wasn’t a side effect reported in studies of the drug.

However, other medications you may be taking to manage your condition, such as corticosteroids, can cause weight gain.

Also, weight changes could be the result of other side effects of Benlysta, such as depression.

If you’re concerned about weight gain while using Benlysta, talk with your doctor. They can help determine the cause.

Can Benlysta cause long-term side effects?

It’s possible. However, long-term side effects are not common with Benlysta.

Long-term side effects may include:

Your risk of these long-term side effects may depend on certain other factors. For example, if you’ve had mood disorders or cancer before, you may have a higher risk of experiencing them with Benlysta.

Tell your doctor about your health history and all the medications you’re taking. They can tell you about the benefits and risks of using Benlysta based on your specific situation.

If you’re prescribed Benlysta, your doctor will monitor you carefully for signs of long-term side effects. They may have you stop Benlysta treatment if you experience serious side effects.

Will I experience hair loss during my Benlysta treatment?

It’s not likely. In studies, hair loss was not reported in people using Benlysta. However, hair loss was reported in people using Benlysta after the drug was approved for use. The condition was reversible once they stopped treatment with Benlysta.

It’s also possible that hair loss may be related to your condition rather than caused by Benlysta. Hair loss is a symptom of lupus, which Benlysta treats.

If you’re concerned about hair loss while using Benlysta, talk with your doctor. They can discuss possible causes and offer suggestions to help manage hair loss. In some cases, they may recommend a different treatment option.

Learn more about the side effects Benlysta may cause.

Depression

Benlysta may cause depression in some people. This was a common side effect reported in studies of the drug.

Symptoms of depression may include:

  • insomnia (trouble sleeping)
  • anxiety
  • feelings of hopelessness or sadness
  • loss of interest in activities you once enjoyed
  • tiredness
  • weight changes
  • suicidal thoughts or behaviors

Depression may also be a side effect of other medications you’re taking.

What might help

If you’ve experienced depression or mood disorders before, tell your doctor before starting Benlysta treatment. They may recommend a different treatment option instead of Benlysta.

If you use Benlysta and you notice mood or behavior changes during your treatment, tell your doctor right away. They’ll likely stop your treatment and have you switch to a different medication.

Also, be sure to tell your doctor if you continue to have depression or other mood changes after you’ve stopped Benlysta treatment. Depending on how severe your condition is, your doctor may recommend treatment for these side effects.

If you have thoughts of suicide, call 911 or your local emergency number. In the United States, you can also call the Suicide and Crisis Lifeline at 988 or text HOME to the Crisis Text Line at 741741.

Diarrhea

Some people may experience diarrhea when using Benlysta. This was a common side effect in studies of the drug. Most cases of diarrhea are mild. But tell your doctor if you have severe diarrhea, as this can lead to dehydration.

Dehydration can cause dizziness, extreme thirst, and reduced urination.

What might help

For mild cases of diarrhea, your doctor may suggest:

  • drinking plenty of fluids to avoid dehydration
  • eating a bland diet, such as the BRAT diet (bananas, rice, applesauce, toast)
  • taking an over-the-counter antidiarrheal medication such as loperamide (Imodium)

If you experience diarrhea that’s severe or doesn’t go away, call your doctor. They’ll discuss treatment options to manage this side effect. In some cases, they may stop your Benlysta treatment and have you switch to a different medication.

Serious infection

Benlysta can raise your risk of infection. In rare cases, serious infections can occur with Benlysta. These include pneumonia, serious urinary tract infection (UTI), bronchitis, or cellulitis.

Benlysta weakens your immune system. This may increase your risk of developing an infection, including a serious one.

Symptoms of infection may include:

In some cases, other medications you may take for lupus could also raise your risk of infection. These include methotrexate and corticosteroids such as prednisone.

What might help

Before you begin treatment with Benlysta, your doctor will run tests to check for infections. If you have an infection, they’ll treat it before you begin using Benlysta.

During your Benlysta treatment, your doctor will monitor you closely for signs of an infection. Tell your doctor if you notice any of the symptoms of infection described above.

If you develop an infection during Benlysta treatment, your doctor will likely have you temporarily stop using the drug. Depending on how severe the infection is, they’ll discuss whether you should continue using Benlysta after the infection is treated.

Allergic reaction

Like most drugs, Benlysta can cause an allergic reaction in some people.

Symptoms can be mild to serious and can include:

  • skin rash
  • itchiness
  • flushing (temporary warmth, redness, or deepening of skin color)
  • swelling under your skin, usually in your eyelids, lips, hands, or feet
  • swelling of your mouth, tongue, or throat, which can make it hard to breathe

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.

Examples include:

  • an antihistamine you swallow, such as Benadryl (diphenhydramine)
  • a product you apply to your skin, such as hydrocortisone cream

If your doctor confirms you’ve had a mild allergic reaction to Benlysta, they’ll decide whether you should continue using it.

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 Benlysta, they may have you switch to a different treatment.

Keeping track of side effects

During your Benlysta 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 using a new drug or using a combination of treatments.

Your side effect notes can include things such as:

  • what dose of the drug you were using 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

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

Benlysta may not be right for you if you have certain medical conditions. These are known as drug-condition interactions. Other factors may also affect whether Benlysta is a good treatment option for you.

Talk with your doctor about your health history before starting Benlysta. Factors to consider include those described below.

Infections. Benlysta may increase your risk of infections, including serious infections such as urinary tract infection (UTI), bronchitis, cellulitis, and pneumonia. In rare cases, serious infections may be life threatening.

For more information, see the “Side effects explained” section above.

Mood disorders. Taking Benlysta may increase your risk of depression or suicidal thoughts or behaviors. Before starting Benlysta treatment, tell your doctor if you have a history of depression or other mood disorders. Your doctor may monitor you closely during treatment for changes in your mood or behavior. In some cases, they may suggest a different treatment for your condition.

For more information on depression, see the “Side effects explained” section above.

Cancer. In rare cases, Benlysta may raise your risk of developing certain types of cancer, including nonmelanoma skin cancer. If you’ve had cancer before, be sure to tell your doctor. They’ll determine whether Benlysta is a safe option for you.

If you do use Benlysta, your doctor will monitor you closely during treatment for signs of cancer.

Taking other biologic medications or monoclonal antibodies. Benlysta is a biologic medication (made from living cells) and belongs to a group of drugs called monoclonal antibodies. It’s not known whether it’s safe to take Benlysta with other biologic drugs or monoclonal antibodies. Before using Benlysta, tell your doctor about all other drugs you take. They can determine whether Benlysta is safe to take with your other medications.

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

Recent vaccines. Before you begin Benlysta treatment, tell your doctor if you’ve recently received any vaccines. You can also ask whether you need to receive any vaccines.

You should not receive any live vaccines during Benlysta treatment or in the 30 days before starting treatment. (Live vaccines contain a small amount of the virus that they’re meant to protect against.) Benlysta weakens your immune system, so receiving a live vaccine could increase your risk of getting sick from the vaccine.

Examples of live vaccines include:

Benlysta may also make non-live vaccines less effective. Examples of these vaccines include:

In some cases, your doctor may suggest getting certain vaccines before you begin treatment with Benlysta.

Alcohol and Benlysta

There is no known interaction between Benlysta and alcohol. But both alcohol and Benlysta can cause nausea, so combining the two may raise your risk of having nausea.

Also, alcohol may interact with other medications you may be taking for your condition. If you drink alcohol, talk with your doctor about how much (if any) may be safe to consume with your treatment plan.

Pregnancy while using Benlysta

It’s not known whether it’s safe to use Benlysta during pregnancy.

Benlysta weakens the immune system. This may affect a fetus or a newborn if you use Benlysta while pregnant. But it’s important to note that untreated systemic lupus erythematosus (one of the conditions Benlysta treats) can also increase pregnancy risks, such as pregnancy loss or premature birth.

If you’re pregnant or planning to become pregnant, talk with your doctor before starting Benlysta treatment. They can help determine whether this drug is right for you.

If you use Benlysta during pregnancy, consider joining the Benlysta MotherToBaby pregnancy registry. A pregnancy registry gathers information about the drug’s effects when used during pregnancy.

You can learn more or sign up on the registry website or by calling 877-311-8972.

In some cases, if you can become pregnant, your doctor may say you should avoid pregnancy during your Benlysta treatment. They’ll recommend using birth control during your treatment and for at least 4 months after your last Benlysta dose.

Breastfeeding while using Benlysta

It’s not known whether Benlysta is safe to use while breastfeeding. If you’re breastfeeding or planning to do so, talk with your doctor before starting Benlysta treatment.

If you still have questions about side effects that Benlysta can cause, talk with your doctor.

Examples of questions you may want to ask include:

  • Am I more likely to have side effects when I first begin treatment with Benlysta?
  • Do the two forms of Benlysta cause different side effects?
  • How do the side effects of Benlysta compare with those of other medications that can treat my condition?

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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.