Mavenclad (cladribine) is a prescription drug used to treat relapsing forms of multiple sclerosis (MS). Mavenclad can cause side effects that range from mild to serious. Examples include: headache and upper respiratory infection.
Mavenclad is used in certain adults* to treat:
The active ingredient in Mavenclad is cladribine. (An active ingredient is what makes a drug work.) The drug comes as a tablet that you swallow.
Keep reading to learn about the common, mild, and serious side effects that Mavenclad can cause. For a general overview of the drug, including details about its uses, see this article.
* Mavenclad is prescribed for people who cannot take other MS drugs or whose MS hasn’t responded well to other MS treatments. It’s also important to note that Mavenclad is not prescribed to treat clinically isolated syndrome.
Some people may experience mild or serious side effects during their Mavenclad treatment. Examples of Mavenclad’s commonly reported side effects include:
- upper respiratory infection (infection of the nose, throat, sinuses, or lungs)
- low levels of lymphocytes (a type of white blood cell)*
- back pain
* To learn more about this side effect, see “Blood cell disorders” in the “Side effects explained” section below.
Like most drugs, Mavenclad can cause mild side effects. Examples of mild side effects that have been reported include:
- back pain
- joint pain
- insomnia (trouble sleeping)
- upper respiratory infection (infection of the nose, throat, sinuses, or lungs)
- hair loss*
* 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 managed, too. But if you have any symptoms that are ongoing or that bother you, talk with your doctor or pharmacist. And don’t stop taking Mavenclad unless your doctor recommends it.
Mavenclad may cause mild side effects other than the ones listed above. See the Mavenclad prescribing information for details.
Note: After the Food and Drug Administration (FDA) approves a drug, it tracks side effects of the medication. If you’d like to notify the FDA about a side effect you’ve had with Mavenclad, visit MedWatch.
Serious side effects can occur with Mavenclad treatment, though they aren’t common.
Serious side effects that have been reported with Mavenclad include:
- heart failure
- liver damage
- serious infection, such as shingles, hepatitis B or C, or tuberculosis (TB), if you’re exposed to any of these viruses or bacteria or have been exposed in the past
- risk of cancer*†
- risk of fetal harm, if taken during pregnancy*‡
- blood cell disorders†
- progressive multifocal leukoencephalopathy (PML, which is a rare, serious brain infection)†§
- allergic reaction†
If you develop serious side effects while taking Mavenclad, 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.
* Mavenclad has a
† To learn more, see the “Side effects explained” section below.
‡ To learn more, see “Pregnancy and breastfeeding while taking Mavenclad” under the “Warnings for Mavenclad” section below.
§ PML was not reported in studies of Mavenclad for MS. But this side effect has been reported in people taking cladribine, Mavenclad’s active drug, for certain cancers.
Get answers to some frequently asked questions about Mavenclad’s side effects.
How long do Mavenclad’s side effects last?
In many cases, mild side effects caused by Mavenclad are temporary. But serious side effects of Mavenclad may last longer (see the question just below for details).
If you have any side effects or symptoms that are ongoing or that bother you, talk with your doctor or pharmacist.
Can Mavenclad cause long-term side effects?
While it’s not common, taking Mavenclad could cause long-term side effects, including:
- certain infections, such as shingles (an infection caused by the chickenpox virus)
- liver damage
Mavenclad may cause long-term side effects other than the ones listed above. See the Mavenclad prescribing information for details. You can also talk with your doctor or pharmacist to learn more about Mavenclad’s long-term side effects.
Can Mavenclad cause swelling in my hands and feet?
Other medications used to treat multiple sclerosis (MS) may cause swelling in the hands or feet. These include Mayzent (siponimod) and corticosteroids such as Rayos (prednisone). But Mavenclad isn’t expected to cause this side effect.
Learn more about some of the side effects Mavenclad may cause.
Treatment with Mavenclad can increase your risk of developing cancer. Mavenclad has a
Cancers reported in people who took Mavenclad in studies included:
Symptoms of cancer vary but can include:
- decreased appetite
- fatigue (low energy)
- skin cuts or scabs that don’t heal
- skin moles that change in color or shape
After you complete two treatment courses* of Mavenclad, doctors won’t prescribe Mavenclad for you again for at least two years. People who took another treatment course of Mavenclad within two years after their first two courses had a higher cancer risk in studies.
If another course of Mavenclad treatment is given two years or more after the first treatment, the risk of cancer isn’t known.
* For more information about Mavenclad’s treatment courses and dosage, see this article.
What might help
Contact your doctor if you notice symptoms of cancer while taking Mavenclad. They can examine you and your symptoms more closely to determine the cause.
If you have cancer, it’s important to let your doctor know before you take Mavenclad. Doctors won’t prescribe Mavenclad if you currently have cancer.
If you’ve had cancer in the past, let your doctor know as well. Together you can discuss the risks and benefits of taking Mavenclad. And, they’ll help determine whether treatment with Mavenclad is safe for you.
What might help
Talk with your doctor if you have hair loss while taking Mavenclad. They may recommend a medication, such as Rogaine (minoxidil), to treat this side effect. Your doctor may also recommend other ways to manage hair loss.
Blood cell disorders
Treatment with Mavenclad can cause certain blood cell disorders as a side effect. Some of these are more common than others. And in many cases, these disorders can be serious.
Blood cell disorders caused by Mavenclad can include low levels of:
- lymphocytes or neutrophils (types of white blood cells)
- hemoglobin (a protein that helps your blood cells transport oxygen)
- platelets (cells that help your blood clot)
Blood cell disorders often don’t cause symptoms, especially when they’re mild. But it’s possible to have symptoms such as a cough, fever, weakness, or fatigue. An infection that won’t go away or swollen lymph nodes (such as in your neck or armpits) could also be symptoms.
What might help
You’ll have a blood test called a complete blood count (CBC) before you start taking Mavenclad. A CBC helps your doctor check your blood cell levels.
You’ll also have CBCs done while you’re taking Mavenclad and after you finish treatment. This helps your doctor monitor for changes in your blood cell levels.
If any of your blood cell levels become low, your doctor will recommend treatment to return them to normal.
Progressive multifocal leukoencephalopathy
An infection called progressive multifocal leukoencephalopathy (PML) has been reported in people taking cladribine. Cladribine is Mavenclad’s active drug.
PML is a rare but life threatening viral brain infection. Symptoms can include:
- changes in your personality, memory, thoughts, or vision
- loss of balance or strength
- weakness on one side of your body
- loss of coordination in your arms and legs
What might help
Before you start taking Mavenclad, you’ll have a test called a magnetic resonance imaging (MRI) scan. This scan produces an image of your brain.
Your doctor will compare this MRI with later scans to check for any changes in your brain, including signs of PML. Changes on an MRI may be noticeable before symptoms of the condition appear.
If you notice symptoms of PML while taking Mavenclad, contact your doctor or get emergency medical help.
Like most drugs, Mavenclad can cause an allergic reaction in some people.
Symptoms can be mild or serious and can include:
- skin rash
- flushing (temporary warmth, redness, or deepening of skin color)
- 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
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 had a mild allergic reaction to Mavenclad, they’ll decide if you should continue taking 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 had a serious allergic reaction to Mavenclad, they may have you switch to a different treatment.
Keeping track of side effects
During your Mavenclad treatment, consider keeping notes on any side effects you’re having. Then, you can share this information with your doctor. This is especially helpful when you first start taking new drugs or using a combination of treatments.
Your side effect notes can include things such as:
- what dose of drug you were taking 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 Mavenclad affects you. And your doctor can use this information to adjust your treatment plan if needed.
Before taking Mavenclad, there are a few important things to talk with your doctor about.
Mavenclad has two
- Cancer. Treatment with Mavenclad may increase your risk of cancer. Due to this risk, doctors typically will not prescribe Mavenclad if you already have cancer. To learn more, see the “Side effects explained” section above.
- Risk of fetal harm. Mavenclad is known to cause fetal harm if taken during pregnancy. To learn more, see “Pregnancy and breastfeeding while taking Mavenclad” below.
Mavenclad 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 take Mavenclad. Some factors to consider are described below.
Current or past infection with tuberculosis, hepatitis B, or hepatitis C. Tell your doctor if you have any chronic (long-term) infections. This includes having tuberculosis (TB), hepatitis B virus, or hepatitis C virus currently or in the past. Taking Mavenclad could cause these viruses to become active infections again, meaning they could start to cause symptoms. Your doctor can determine whether treatment with Mavenclad is safe for you.
History of chickenpox or shingles. If you’ve had chickenpox or shingles in the past, be sure your doctor knows this. The varicella (chickenpox) vaccine is recommended before starting Mavenclad treatment. Mavenclad can increase your risk of infections such as shingles. The varicella vaccine can help protect you from developing shingles while you’re taking Mavenclad. In some cases, your doctor might give you this vaccine during Mavenclad treatment instead.
HIV. Doctors typically won’t prescribe Mavenclad if you have HIV. This is because Mavenclad reduces the activity of your immune system, making it harder for your body to fight HIV. You and your doctor can discuss other treatments for your MS instead.
Kidney problems. Mavenclad may not be safe to take if you have certain kidney problems. These include moderate or severe chronic kidney disease. This is because having certain kidney problems makes it harder for your body to get rid of Mavenclad after a dose. This can raise your risk of side effects. Your doctor can help determine whether Mavenclad is safe for you to take.
Liver problems. Mavenclad can rarely cause liver damage as a side effect. Tell your doctor if you have liver problems (such as hepatitis) before you take Mavenclad. Your doctor may monitor you closely during treatment, or they may decide another MS treatment would be safer for you.
Heart problems. Heart problems, including heart failure, have been reported with Mavenclad. Tell your doctor if you have heart problems before you start Mavenclad treatment. And if you have any symptoms of heart failure while taking Mavenclad, contact your doctor or get emergency medical help. Symptoms may include shortness of breath, swelling, or a fast or irregular heart rate.
Recent live vaccination. You should wait at least 4 to 6 weeks after receiving a live vaccine before taking Mavenclad. (Live vaccines contain a small amount of weakened live virus or bacteria.) Mavenclad reduces the activity of your immune system and could cause you to get sick after getting certain vaccines. Your doctor or pharmacist can tell you more about vaccines and Mavenclad.
Allergic reaction. If you’ve had an allergic reaction to Mavenclad or any of its ingredients, your doctor will likely not prescribe Mavenclad. Ask your doctor what other medications are better options for you.
Alcohol and Mavenclad
There’s no known direct interaction between treatment with Mavenclad and drinking alcohol.
However, drinking alcohol could raise your risk of liver damage, which is a side effect of Mavenclad.
Talk with your doctor if you drink alcohol. They can advise you on how much may be safe for you to drink while you’re taking Mavenclad.
Pregnancy and breastfeeding while taking Mavenclad
Mavenclad isn’t safe to take during pregnancy or while breastfeeding. You also should not take Mavenclad if you’re planning to become pregnant or not using effective birth control. You should avoid breastfeeding for at least 10 days after your last dose of Mavenclad.
Risk of fetal harm
Mavenclad has a boxed warning about risk of fetal harm (commonly called birth defects) if taken during pregnancy. A boxed warning is the most serious warning from the Food and Drug Administration (FDA).
Studies of animals given Mavenclad during pregnancy found that the drug caused severe harm or death to offspring. The drug hasn’t been studied in pregnant humans. This is because the risks shown in animal studies are too severe.
If you’re able to become pregnant, you’ll take a pregnancy test before starting Mavenclad treatment. This is to make sure you aren’t pregnant.
It’s also not safe to become pregnant for at least 6 months after your last dose of Mavenclad. If you can become pregnant, or have a sexual partner who can become pregnant, you should use birth control:
- while taking Mavenclad, and
- for at least 6 months after your last dose of each yearly treatment course
Talk with your doctor if you take birth control by mouth (also called oral contraception, or “the pill”). You should use a second method of birth control on the days you take Mavenclad and for at least 4 weeks after your last dose of each yearly treatment course.
If you become pregnant while taking Mavenclad, stop taking the medication and contact your doctor right away.
If you have certain forms of multiple sclerosis (MS), your doctor may recommend treatment with Mavenclad. You can talk with your doctor or pharmacist if you’re interested in learning more about the drug’s side effects or effectiveness.
Ask the questions to get the answers you need to feel confident about your MS treatment. Some questions to consider asking are:
- Are there ways I can lower my risk of side effects from Mavenclad?
- If I develop side effects while taking Mavenclad, can my dose be lowered?
- Do other medications I take raise my risk of side effects with Mavenclad?
- Are there lab tests or blood tests I’ll need while taking Mavenclad to monitor for side effects?
To learn more about Mavenclad, see these articles:
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Are there steps I can take to reduce my risk of infection while I’m being treated with Mavenclad?Anonymous
Mavenclad is known to increase the risk of serious infection. To lower your risk, be sure to tell your doctor about all of your medical conditions, including any infections you have.
Also tell your doctor about all the medications you take. Certain drugs can increase your risk of infection with Mavenclad.
You can also talk with your doctor about getting certain vaccines before starting Mavenclad to help prevent infection. For example, it’s recommended that you receive the varicella (chickenpox) vaccine before starting Mavenclad treatment.
It’s important to keep in mind that you should wait at least 4 to 6 weeks after receiving a live vaccine before taking Mavenclad. (Live vaccines contain a small amount of weakened live virus or bacteria.) The varicella vaccine is an example of a live vaccine. Your doctor can help determine whether you need any vaccines, including live vaccines.
Depending on the results of certain tests, your doctor might also prescribe medications to help prevent certain infections while you take Mavenclad.
Tell your doctor right away if you have symptoms of an infection with Mavenclad or after a treatment course. Symptoms can include fever, headache, feeling unwell, muscle pain, or loss of appetite. Your doctor will make sure to monitor you and treat any symptoms as needed.The Healthline Pharmacist TeamAnswers represent the opinions of our medical experts. All content is strictly informational and should not be considered medical advice.
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.