Cosentyx (secukinumab) can cause side effects that range from mild to serious. More common side effects include infections, diarrhea, and hives. If side effects from Cosentyx become difficult to manage, talk with your doctor.

Cosentyx injections are approved by the Food and Drug Administration (FDA) to treat:

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

Cosentyx can cause certain side effects, some more common than others. These side effects may be temporary, lasting a few days to weeks. Talk with your doctor if side effects do not go away, get worse, or become too difficult for you to tolerate.

Cosentyx’s commonly reported side effects include:

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

In most cases, these side effects should be temporary, and some may be easily managed. But if you have symptoms that are ongoing or bothersome, talk with your doctor or pharmacist. Do not stop using Cosentyx unless your doctor recommends it.

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

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

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

If you develop serious side effects while using Cosentyx, 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 of Cosentyx may include:

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

Note: After the Food and Drug Administration (FDA) approves a drug, it tracks and reviews side effects of the medication. Sharing your experience helps make medication safer for everyone by giving doctors and researchers more information about how the drug works in real life. If you develop a side effect while using Cosentyx and want to tell the FDA about it, visit MedWatch or call 800-FDA-1088.

Allergic reaction

For some people, Cosentyx 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 using Cosentyx.

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

While using Cosentyx, you may be able to take steps to make side effects easier to manage.

If you have problems with side effects, they do not go away, or they become worse, talk with your doctor or pharmacist. They can discuss options for managing side effects or other available treatment options.

Bacterial, fungal, or viral infections

Cosentyx can make it harder for your immune system to fight against germs. This could raise your risk of bacterial, fungal, or viral infections. These infections may be mild or serious.

Mild infections are a common side effect of Cosentyx. Examples include upper respiratory infections (such as the common cold) and cold sores. In most cases, these infections should go away on their own. You’ll likely only need treatment to relieve your symptoms.

In rare cases, Cosentyx can cause serious infections. These may include:

You’ll likely need treatment to clear these infections.

Note: TB is a rare but serious bacterial infection that primarily affects the lungs. Your doctor will check you for TB before and during your Cosentyx treatment. If you’ve had TB in the past, tell your doctor. Drugs that affect your immune system, such as Cosentyx, may cause a latent TB infection (TB that’s in your body but isn’t causing symptoms) to become active again.

What might help

Here are a few steps you can take to help prevent infection while using Cosentyx:

  • Wash your hands often. (Use hand sanitizer if soap and water aren’t available.)
  • Avoid crowds during cold and flu season.
  • Stay up to date on vaccines (but see the note later in the article for certain exceptions).
  • Eat a balanced diet.
  • Keep your doctor and lab appointments.
  • Contact your doctor if you feel sick or have a fever.

Call your doctor if you have any symptoms of infection, even if they seem mild. Your doctor will check for a serious infection and treat it if needed.

In some cases, your doctor may stop your Cosentyx treatment until your infection has cleared. But do not stop using Cosentyx unless your doctor recommends it.

Note: Because Cosentyx may weaken your immune system, you shouldn’t get live vaccines during your treatment. Live vaccines contain a weakened form of a virus or bacteria, and they could cause infection in someone with a weakened immune system. Examples of live vaccines include smallpox, chickenpox, and measles, mumps, rubella (MMR) vaccines.

Before starting Cosentyx, talk with your doctor about any vaccines you may need.

Inflammatory bowel disease

In rare cases, Cosentyx can cause IBD. If you already have IBD, Cosentyx may cause flare-ups that could be severe.

IBD describes a group of conditions that cause inflammation (swelling or damage) in certain parts of your digestive system. Crohn’s disease and ulcerative colitis (UC) are common types of IBD.

What might help

Before starting Cosentyx, tell your doctor if you have Crohn’s disease, UC, or another type of IBD. It’s important to mention your IBD even if it’s in remission (which means you’re not currently experiencing symptoms). Your doctor may monitor you more closely during your treatment, or they may choose another treatment for your condition.

While using Cosentyx, watch for IBD symptoms. Tell your doctor right away if you have new or worsening:

  • abdominal pain or cramping
  • bloating or gas
  • blood or mucus in your stool
  • constipation
  • diarrhea
  • mouth ulcers
  • nausea

Before starting Cosentyx, talk with your doctor about your IBD risk and symptoms to watch for.

Diarrhea

Diarrhea is a common side effect of Cosentyx. However, diarrhea is also a symptom of IBD, which is a rare but serious side effect of Cosentyx.

What might help

Diarrhea that’s not caused by IBD should go away in a few days to a couple of weeks.

Until then, stay hydrated and consider following the BRAT diet. (BRAT stands for bananas, rice, applesauce, and toast.) These are bland foods that shouldn’t upset your digestive system, and they can bulk up your stools. You can also ask your doctor whether it’s safe to use over-the-counter diarrhea treatments.

In some cases, diarrhea may be a sign of IBD, which is a serious side effect of Cosentyx. Contact your doctor if your diarrhea doesn’t go away or gets worse. But be sure to call them right away if you see blood or mucus in your stool.

Latex allergy

Two forms of Cosentyx, the Sensoready Pen and prefilled syringes, have removable caps that contain latex. If you have a latex allergy, you may be sensitive to these forms of the drug.

Allergic reaction to latex wasn’t tested in studies of Cosentyx, so it’s unclear how often this effect may occur.

What might help

If you have a latex allergy, talk with your doctor before using Cosentyx. You may need to receive Cosentyx injections with a latex-free syringe in your doctor’s office instead of giving yourself the injections at home. Or your doctor may prescribe a different treatment for your condition.

If you have a mild latex allergy and use the pen or prefilled syringe to self-inject at home, watch for symptoms of allergic reaction. These symptoms include hives and skin rash. If you have side effects that feel serious or life threatening, call 911 or your local emergency phone number, or get emergency medical care.

Hives

In rare cases, Cosentyx may cause hives (itchy welts on your skin). Hives are a common symptom of an allergic reaction.

What might help

With mild allergic reactions, hives usually go away without treatment. If you’re uncomfortable, try cold compresses (unless cold makes your hives worse) or calamine lotion.

But if your hives are severe, or if you have other symptoms of an allergic reaction (such as swelling), contact your doctor. They may prescribe treatment such as an antihistamine. If your symptoms feel life threatening, call 911 or your local emergency phone number, or get medical care right away.

If your doctor confirms you’re having an allergic reaction, they may stop your Cosentyx treatment. But do not stop receiving this drug unless your doctor recommends it.

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

Is fatigue a side effect of Cosentyx?

No, Cosentyx shouldn’t cause fatigue. Fatigue wasn’t seen in studies of Cosentyx.

However, fatigue is a side effect of methotrexate (Trexall, Rasuvo, Otrexup), which you may use with Cosentyx. Fatigue can also be a symptom of psoriatic arthritis and other conditions that Cosentyx treats.

If you experience fatigue that bothers you, talk with your doctor. They’ll check your overall health and review your medications. Do not stop or change your Cosentyx treatment unless your doctor recommends it.

Can the Cosentyx injection cause side effects?

It’s possible. Injection-site reactions weren’t seen in studies, but in general, injected drugs such as Cosentyx may cause certain side effects. An example is skin irritation.

Cosentyx comes as a solution that’s given as a subcutaneous injection (an injection given under the skin) or as an intravenous (IV) infusion (an injection into a vein given slowly over time). It’s possible to experience mild or temporary swelling, discoloration, or pain at the injection site.

It’s also important to note that the Cosentyx Sensoready Pen and prefilled syringes have removable caps that contain latex. If you have a latex allergy, you may be sensitive to these forms of the drug. Talk with your doctor about your risk of injection-site reactions with Cosentyx. You may need to receive Cosentyx injections with a latex-free syringe in your doctor’s office instead of giving yourself the injections at home.

If you’re having trouble injecting Cosentyx, ask your doctor or pharmacist for tips. And for more help with self-injecting Cosentyx, see the manufacturer’s instructions for use.

Can Cosentyx cause weight loss?

No, it’s unlikely that Cosentyx causes weight loss. This side effect wasn’t seen in studies of Cosentyx.

Weight loss is a common side effect of apremilast (Otezla), which is also used to treat plaque psoriasis and psoriatic arthritis in adults.

Additionally, weight loss may be a symptom of an infection. And infections are a possible side effect of Cosentyx.

If you have unexplained weight loss while using Cosentyx, talk with your doctor. They’ll check your overall health and review your medications. Do not stop or change your Cosentyx treatment unless your doctor recommends it.

Can depression be a side effect of Cosentyx?

No, Cosentyx shouldn’t cause depression or mood changes. These side effects weren’t seen in studies of Cosentyx.

Other drugs used to treat your condition may cause depression. Examples of these drugs include:

  • Brodalumab (Siliq), which treats plaque psoriasis and may raise your risk of depression and suicidal thoughts or behaviors. This drug works the same way in your body as Cosentyx.
  • Corticosteroids, such as prednisone (Rayos), treat psoriatic arthritis and other autoimmune diseases. Corticosteroids may cause mood changes and depression, especially when they’re taken too long or in high doses.

In addition, autoimmune diseases such as psoriasis are linked with depression and mental health conditions.

Depression is a serious condition that should not be ignored. If you think you have depression or another mental health condition, call your doctor as soon as possible. Symptoms of depression may include anxiety, mood changes, loss of appetite, or feeling angry or irritable.

Help is out there

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

  • Call or text the 988 Suicide and Crisis Lifeline at 988 or chat at 988lifeline.org. Caring counselors are available to listen and provide free and confidential support 24/7.
  • Text HOME to the Crisis Text Line at 741741 to connect with a volunteer crisis counselor for free and confidential support 24/7.
  • Not in the United States? Find a helpline in your country with Befrienders Worldwide.
  • Call 911 or your local emergency services number if you feel safe to do so.

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’re not in the same household, stay on the phone with them until help arrives.

I’m having some hair loss. Could Cosentyx be causing it?

No, Cosentyx shouldn’t cause hair loss. Hair loss wasn’t seen in studies of Cosentyx.

But hair loss is a side effect of methotrexate (Trexall, Rasuvo, Otrexup), which is sometimes used with Cosentyx. And in rare cases, other biologic drugs, such as adalimumab (Humira), may cause hair loss. (Cosentyx is also a biologic drug, which is a drug made from living cells.)

In addition, plaque psoriasis can form itchy patches on your scalp. Itching can cause hair loss. But once the patches decrease, your strands should grow back.

If you’re concerned about hair loss while using Cosentyx, talk with your doctor.

How quickly can side effects of Cosentyx start?

Based on studies, side effects can begin during the first 12 weeks after starting treatment with Cosentyx. If you’re experiencing a side effect that is bothersome, contact your doctor right away. They can discuss whether you should continue Cosentyx or switch to another treatment for your condition.

Keeping track of side effects

During your Cosentyx treatment, consider keeping notes on any side effects you’re having. Then, you can share this information with your doctor. This is especially helpful to do when you first start taking new drugs or using a combination of treatments.

Your side effect notes can include things like:

  • what dose of drug you were receiving when you had the side effect
  • how soon after starting that dose you had the side effect
  • what your symptoms were from the side effect
  • how it affected your daily activities
  • what other medications you were also taking
  • any other information you feel is important

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

Cosentyx may not be right for you if you have certain medical conditions or other factors that affect your health. Talk with your doctor about your health history before you start receiving Cosentyx. Here is the list of the factors to consider before starting your Cosentyx treatment.

Inflammatory bowel disease: If you have a type of IBD such as Crohn’s disease or ulcerative colitis, talk with your doctor before using Cosentyx. This drug may cause serious IBD flare-ups. Your doctor may monitor you closely during your treatment, or they may choose another treatment for your condition. While using Cosentyx, tell your doctor right away about any new or worsening IBD symptoms, including bloating, gas, and blood or mucus in your stools.

Allergy to latex: If you have a latex allergy, talk with your doctor before using Cosentyx. Two forms of Cosentyx, the Sensoready Pen and prefilled syringes, have removable caps that contain latex. If you have a latex allergy, you may be sensitive to these forms of the drug. Ask whether you should receive Cosentyx injections with a latex-free syringe in your doctor’s office or if you can give yourself injections at home.

Infection: If you have an infection, your doctor may need to treat it before you start using Cosentyx. This is because the drug can raise your risk of infections, including tuberculosis (TB). Tell your doctor if you’ve had TB before. Your doctor will check you for TB before and during your Cosentyx treatment.

Allergic reaction: If you’ve had an allergic reaction to Cosentyx or any of its ingredients, you shouldn’t receive Cosentyx. Ask your doctor what other medications are better treatment options.

Alcohol and Cosentyx

If you drink alcohol, it should be safe to drink during Cosentyx treatment.

However, alcohol can damage your liver. A drug that’s used with Cosentyx, methotrexate (Trexall, Rasuvo, Otrexup), can also harm your liver. Drinking alcohol with methotrexate can raise your risk of liver problems. So you should avoid alcohol if you’re using methotrexate to treat your condition.

Also, alcohol may trigger the condition you’re using Cosentyx to treat, such as plaque psoriasis and psoriatic arthritis.

If you drink alcohol, talk with your doctor about how much is safe for you to drink with your condition and treatment plan.

Pregnancy and breastfeeding while using Cosentyx

It’s unknown whether Cosentyx is safe to use during pregnancy or while breastfeeding.

If you’re pregnant or breastfeeding, or planning to become pregnant or to breastfeed, talk with your doctor before using Cosentyx.

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.