7 Bimzelx Side Effects: Upper Respiratory Infections, Oral Thrush, and More

There are many ways to treat autoimmune conditions. And several new treatment options have become available for them over the past few years — many of them biologics.

Your dermatologist or rheumatologist may have prescribed you Bimzelx (bimekizumab-bkzx), a biologic medication that treats health conditions such as hidradenitis suppurativa, psoriatic arthritis, and more. This injectable medication works by blocking a chemical messenger called interleukin-17, which is responsible for promoting inflammation.

Bimzelx is an effective treatment overall, but there are some side effects you should be wary of during the course of your treatment. 

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Bimzelx side effects at a glance

The most common Bimzelx side effects you may experience include:

• Upper respiratory tract infections (URTIs)

• Oral candidiasis (thrush)

• Headaches

• Cold sores

• Pain and swelling at the injection site

• Acne

• Urinary tract infections

URTIs and oral thrush are the most common Bimzelx side effects. Most other Bimzelx side effects, such as headaches and injection site reactions, occur infrequently — even though they were commonly seen in clinical studies.

Bimzelx can also cause rare but serious side effects, such as:

• Liver problems

• Serious infections

• Suicidal thoughts and behaviors

Let’s review seven of these Bimzelx side effects and how to manage them.

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1. Upper respiratory tract infections

Upper respiratory tract infections (URTIs) are among the most common side effects of Bimzelx. They include illnesses such as the common cold, strep throat, and flu. 

Bimzelx works by suppressing your immune system to treat inflammatory health conditions. At the same time, though, this can make you more prone to infections — especially during the cold and flu season. 

You can take a few steps to reduce your chances of becoming sick while receiving Bimzelx. Practice good hand hygiene, avoid contact with sick people, and get your vaccinations as scheduled. Don’t be afraid to mask up in crowded areas, either, such as an airplane.

Speak to a healthcare professional if you experience fever, cough, or other symptoms of infection. They can let you know if you can take over-the-counter (OTC) medications, such as acetaminophen (Tylenol), to ease your symptoms, or if other treatments are necessary.

2. Oral thrush

Oral thrush often appears as white spots on the tongue, inner cheeks, or other areas inside your mouth. These white spots are signs of a fungal infection called candidiasis, which is caused by Candida — a fungus that naturally lives in your mouth. 

Oral thrush happens when the natural balance of Candida in your mouth is disrupted. This can happen due to medications (including Bimzelx), dry mouth, and other potential causes. Your age, health conditions, and health procedures, such as radiation therapy, are other possible risk factors.

Your specialist can prescribe an antifungal medication, such as nystatin, to help combat oral thrush if it develops. They may also recommend specific measures for lessening oral thrush moving forward. For example, they may suggest chewing gum, sucking on ice chips, and taking other nonmedication interventions to increase saliva production if you have a dry mouth.

3. Injection site reactions

Injection site reactions are common side effects of medications that are injected under the skin. Bimzelx is no exception.

Bimzelx is injected into your stomach area (abdomen), thighs or the back of your upper arms. You may experience pain, redness, and swelling around the area where you injected Bimzelx. Other possible side effects are bruising and/or swelling at the injection site.

Injection site reactions usually resolve on their own over the course of a few days. However, you can use ice packs; OTC medications, such as ibuprofen (Advil, Motrin); and other treatments for more immediate relief if you’re having bothersome symptoms. 

Hives, difficulty breathing, and swelling of the lips or face are symptoms of something more serious, such as a hypersensitivity or anaphylactic reaction. This is different from an injection site reaction; anaphylaxis is a medical emergency. Call 911 or go to the nearest ER if you or a caregiver notice that you’re having any possible symptoms of anaphylaxis.

4. Headaches

Headaches can show up for all kinds of reasons, such as being dehydrated, having an infection, or even just having a stressful day. 

Sometimes, medications such as Bimzelx are the culprit behind headaches, too. A small percentage of people experienced headaches in Bimzelx’s clinical studies. 

Several treatment options are available to treat headaches. They include OTC medications, such as acetaminophen, and nonmedication interventions, such as meditation and breathing exercises. Dietary changes, such as drinking plenty of water and reducing alcohol consumption, can also play a role in headache management.

It may be time to talk to a healthcare professional if your headaches don’t resolve with these measures. They can walk you through other headache treatments, including prescription medications.

5. More serious infections

Mild infections are relatively common while receiving Bimzelx. But it’s important to be aware of the possibility of more serious infections, too, even though they’re rare. 

If you’re new to Bimzelx, tell your specialist if you have active symptoms of an infection, such as fever or fatigue. They may want you to wait until you feel better before starting Bimzelx. This is done out of caution to help make sure the infection doesn’t get any worse. They will also likely evaluate you for tuberculosis (TB) before you start Bimzelx; TB is a bacterial lung infection.

What’s more, speak to your specialist right away if you have any infection symptoms — such as a fever, cough, or blood in your phlegm — after starting Bimzelx. They can walk you through how to treat the infection and if you should seek medical attention.

6. Liver problems

Bimzelx can cause liver problems in rare cases. These issues often don’t show symptoms. But make sure to tell your specialist if you experience symptoms of liver problems, such as pain on the right side of your stomach, dark urine, and/or light-colored stools. Other symptoms include yellowing of the skin and eyes, tiredness, and fatigue.

Your prescriber should also run blood tests to check your liver enzyme levels before you start Bimzelx. They should periodically check your labs while you’re taking it, too. Your specialist may pause or stop your Bimzelx treatment to ensure that your liver stays safe if your blood tests start to become abnormal. Also make sure to tell them if you have any current or previous liver problems, such as cirrhosis or liver disease.

7. Mood changes, including thoughts of suicide

It’s not clear if Bimzelx actually causes new or worsening suicidal thoughts. However, some people in Bimzelx’s clinical trials did experience them.

Speak to your specialist, as well, if you’re having mood changes. New or worsening depression, anxiety, and thoughts of hurting yourself are other symptoms to be aware of. Your specialist may want you to stop taking Bimzelx and switch to another treatment option.

You or your caregiver can also call the Suicide & Crisis Lifeline at 988 if you develop thoughts of suicide (or if you have risky changes in your behavior).

Why trust our experts?

Written by:

Mandeep Sohal, PharmD

Mandeep Sohal, PharmD, has more than 7 years of experience in the pharmaceutical industry and is licensed in California. In his career, he’s had experience with specialty pharmacy, community pharmacy, pharmacy benefit management, and pharmaceutical manufacturers.

Edited by:

Joshua Murdock, PharmD, BCBBS

Joshua Murdock, PharmD, BCBBS, is a licensed pharmacist in Arizona, Colorado, and Rhode Island. He has worked in the pharmacy industry for more than 10 years and currently serves as a pharmacy editor for GoodRx.

Reviewed by:

Austin Ulrich, PharmD, BCACP

Austin Ulrich, PharmD, BCACP, is a board-certified ambulatory care clinical pharmacist. In his early career, he provided direct patient care in a variety of settings, including hospital and community pharmacies, and in a primary care clinic as a clinical pharmacist.

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