Bimzelx (bimekizumab-bkzx) is a prescription drug used to treat plaque psoriasis. Bimzelx can cause side effects that range from mild to serious. Examples include headache, injection site reaction, and upper respiratory tract infection.

Specifically, Bimzelx is a biologic drug (made from living cells) prescribed to treat moderate to severe plaque psoriasis in adults. If this medication works for you, your doctor will likely recommend it as a long-term treatment.

The active ingredient in Bimzelx is bimekizumab-bkzx.* (An active ingredient is what makes a drug work.) The drug comes as a liquid solution you inject under your skin using a prefilled syringe or an auto-injector.

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

* The reason “-bkzx” appears at the end of the drug’s name is to show that the drug is distinct from similar medications that may be created in the future.

Some people may experience mild to serious side effects during Bimzelx treatment. Here are a few examples of the drug’s commonly reported side effects:

* While Bimzelx itself does not cause viral, yeast, or other forms of infection, this drug can reduce your body’s ability to fight infection. This means treatment with this medication can increase your risk of acquiring certain conditions.
† To learn more about this side effect, see the “Side effects explained” section below.

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 Bimzelx, visit MedWatch.

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

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

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

* While Bimzelx itself does not cause viral, yeast, or other forms of infection, this drug can reduce your body’s ability to fight infection. This means treatment with this medication can increase your risk of acquiring certain conditions.
† To learn more about this side effect, see the “Side effects explained” section below.
‡ An allergic reaction is possible after injecting Bimzelx, but this side effect wasn’t reported in studies.

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

If you develop serious side effects during Bimzelx 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.

* While Bimzelx itself does not cause viral, yeast, or other forms of infection, this drug can reduce your body’s ability to fight infection. This means treatment with this medication can increase your risk of acquiring certain conditions.
To learn more about this side effect, see the “Side effects explained” section below.
‡ An allergic reaction is possible after injecting Bimzelx, but this side effect wasn’t reported in studies.

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Get answers to some frequently asked questions about side effects of Bimzelx.

How long do side effects of Bimzelx usually last?

Injection site reactions usually resolve in a few days. Headaches may be short term and can often be treated with over-the-counter acetaminophen. If you have a chronic (long-term) headache or an injection site reaction lasting longer than 2–3 days, contact your doctor. These symptoms may require a medical evaluation.

Bimzelx suppresses your immune system, which can make you more susceptible to infections. These may last for a usual amount of time, or they may become chronic. Infections include:

  • oral or genital herpes
  • tuberculosis (TB)
  • upper respiratory tract, skin, or yeast infection

Most infections can be treated with prescription drugs, so letting your doctor know about an infection early on may make it easier to manage. Symptoms of a severe infection requiring prompt medical attention include:

Talk with your doctor or pharmacist to learn more about possible side effects of Bimzelx and how long they may last.

Does Bimzelx cause long-term side effects?

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

Examples of long-term side effects reported in Bimzelx’s studies include:

  • chronic infection, such as:
    • mouth, skin, or genital yeast infection
    • upper respiratory tract infection
    • acne or infected hair follicles
    • herpes simplex of the mouth or genitals
  • nail or foot fungus
  • inflammatory bowel disease*
  • suicidal thoughts or behaviors
  • increased liver enzymes

If you’re concerned about possible long-term side effects from Bimzelx, talk with your doctor or pharmacist.

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

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

Injection site reaction

Injection site reactions were a common side effect reported in studies of Bimzelx. Injection site reactions may cause symptoms such as:

  • itching
  • a hard skin lump
  • warmth at the injection site
  • swelling
  • bruising or skin discoloration
  • pain or tenderness at the injection site

Factors that can increase the risk of injection site reactions with this drug include:

  • injecting Bimzelx that’s colder than the room temperature
  • incorrect injection site or technique

What might help

If you have injection site reactions during Bimzelx treatment, the following tips may help prevent your symptoms:

  • Watch this video on the correct Bimzelx injection technique.
  • Avoid injecting into or near areas that have rashes, scars, or bruises.
  • Allow Bimzelx to sit at room temperature for 30 minutes before injecting it.
  • Avoid harsh rubbing of the injection site.
  • Apply a cool compress to a swollen, discolored injection site.

If you have an injection site reaction lasting longer than 2–3 days, contact your doctor, as these symptoms may need a medical evaluation.

Inflammatory bowel disease

Inflammatory bowel disease (IBD) was an uncommon but serious side effect reported in studies of Bimzelx. IBD may cause symptoms such as:

Factors that can increase the risk of developing IBD with Bimzelx treatment include:

  • viral or bacterial infection
  • personal or family history of IBD
  • smoking
  • diet high in saturated fats and processed foods
  • being younger than 35 years old
  • belonging to a certain ethnic group, such as white, Ashkenazi Jew, or Black
  • having a sedentary lifestyle or job
  • living in a cold climate or urban setting

What might help

If you have symptoms of IBD during Bimzelx treatment, talk with your doctor right away. They’ll likely recommend an urgent medical evaluation.

Allergic reaction

Like most drugs, Bimzelx can cause an allergic reaction in some people, but this side effect wasn’t reported in studies. 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 oral antihistamine, 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 Bimzelx, they’ll decide whether you should continue treatment with it.

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

Keeping track of side effects

During your Bimzelx 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 taking 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 injecting 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 Bimzelx affects you. They can then use this information to adjust your treatment plan if needed.

Below is important information you should consider before starting Bimzelx.

Warnings

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

Talk with your doctor about your health history before starting treatment with this medication. Be sure to tell them if any of the following factors apply to you:

  • history of depression, or suicidal thoughts or behaviors
  • history of TB or other active or chronic (long-term) infection
  • liver problems
  • live vaccine received within the past 14 days
  • history of inflammatory bowel disease
  • past allergic reaction to Bimzelx
  • pregnancy
  • breastfeeding

Alcohol and Bimzelx

There are no known interactions between alcohol and Bimzelx. However, liver problems can occur from both Bimzelx and over-consumption of alcohol. Your risk of liver damage increases if you drink too much or too often during treatment with this medication.

If you have questions about consuming alcohol during Bimzelx treatment, talk with your doctor or pharmacist.

Pregnancy and breastfeeding with Bimzelx

Bimzelx is usually prescribed for someone who’s pregnant or breastfeeding only if the benefits of treatment outweigh the potential risks to the fetus or child.

Pregnancy

There isn’t enough information about Bimzelx and pregnant people to assess whether it’s safe for use during pregnancy. The drug passes from the pregnant person to their developing fetus in increasing amounts as the pregnancy progresses. This means the fetus can be exposed at the highest level in the last few months of pregnancy. But it’s not known how the drug affects the fetus.

If you’re able to become pregnant, your doctor may recommend using a form of birth control before, throughout, and for 17 weeks after treatment with Bimzelx.

If you have treatment with this drug while pregnant, consider signing up for the MotherToBaby Pregnancy Studies by visiting the website or calling 877-311-8972. This is a pregnancy registry that collects information about the safety of certain drugs when taken or used during pregnancy.

If you’re pregnant or planning to become pregnant, talk with your doctor before starting treatment with Bimzelx.

Breastfeeding

It isn’t known whether Bimzelx is safe for use while breastfeeding. There’s no information on the amount of Bimzelx that passes into breast milk, how it affects milk production, or its effects on children who are breastfed.

If you’re breastfeeding or planning to do so, talk with your doctor before starting this medication. They can help you determine the best options for feeding your child and treating your condition.

Like most drugs, Bimzelx can cause a number of side effects that range from mild to serious. Most are temporary and go away after a few days to weeks. If you have questions about side effects this drug can cause, talk with your doctor. Examples to help get you started include:

  • Can Bimzelx cause blood problems or anemia (low level of red blood cells)?
  • When should I contact you about side effects I’m having with Bimzelx?
  • Can Bimzelx cause permanent liver damage?
  • What over-the-counter drugs can I take to treat side effects of Bimzelx?

To get information on different conditions and tips for improving your health, subscribe to any of Healthline’s newsletters. You may also want to check out the online communities at Bezzy. It’s a place where people with certain conditions can find support and connect with others.

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.