Litfulo (ritlecitinib) is a prescription oral capsule used to treat severe alopecia in adults and certain teenagers. Litfulo can cause side effects that range from mild to serious. Examples include headache and skin rash.

Keep reading to learn about the common, mild, and serious side effects Litfulo 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 Litfulo treatment.

Examples of the drug’s more commonly reported side effects include:

Mild side effects have been reported with Litfulo. 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. And do not stop taking Litfulo unless your doctor recommends it.

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

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

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

If you develop serious side effects while taking Litfulo, 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.

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

Note: After the 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 Litfulo, visit MedWatch.

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

How do side effects of Litfulo compare with those of Olumiant?

Litfulo and Olumiant (baricitinib) are both prescribed to treat severe alopecia. They belong to the same group of drugs (JAK inhibitors) and can cause some similar side effects.

For example, both drugs can increase the risk of serious infection, cancer, blood clots, and cardiovascular problems such as heart attack and stroke*. Mild side effects of both drugs are also similar.

However, Olumiant can cause some side effects that haven’t been reported with Litfulo. These include perforations (tears) in the stomach or intestine, increased cholesterol, and weight gain.

To learn more about how Litfulo and Olumiant compare, talk with your doctor.

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

Does Litfulo cause long-term side effects?

It’s possible. Examples of long-term side effects reported in Litfulo’s studies include the risk of serious infection and cancer. (See the “Side effects explained” section just below for more information.)

These side effects can continue for as long as you take Litfulo. They can also last for a long time after you’ve stopped taking the medication.

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

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

Boxed warnings

Litfulo has boxed warnings about the risks described below. Boxed warnings are the most serious warnings from the FDA. They alert doctors and patients about drug effects that may be dangerous.

Risk of serious infection

Litfulo can increase your risk of infections, including serious and even life threatening infections such as tuberculosis (TB). These infections may need to be treated in a hospital. Infections were a common side effect reported in studies of Litfulo, but serious infections were rare.

Examples of serious infections that have been reported with Litfulo include:

Infections may cause symptoms such as:

Factors that can increase the risk of serious infection when taking this drug include:

What might help

Before starting Litfulo, tell your doctor about any infections you currently have and about any past, recurring, or ongoing infections you’ve had. Tell them if you’ve ever had chickenpox or shingles and talk with them about your immunization history. They may want to test for TB before prescribing Litfulo for your condition.

Your doctor may prescribe medication to treat any infections you have before you start Litfulo. They may also recommend getting certain immunizations.

If you have symptoms of an infection during Litfulo treatment, talk with your doctor. They may prescribe medication to treat the infection and recommend you stop taking Litfulo until the infection clears up.

Increased risk of death

Drugs from the same group as Litfulo (JAK inhibitors) can increase the risk of death in certain people who take them for rheumatoid arthritis. Keep in mind that Litfulo is not approved to treat rheumatoid arthritis.

The increased risk of death with other JAK inhibitors was reported in people ages 50 years and older with at least one heart disease risk factor. Examples include:

It’s not known whether Litfulo can increase the risk of death. This side effect wasn’t reported in Litfulo studies.

What might help

Before starting Litfulo, talk with your doctor about your age and any heart disease risk factors you may have. Your doctor will consider these factors before deciding whether Litfulo is right for you.

Risk of cancer

Drugs from the same group as Litfulo (JAK inhibitors) may increase the risk of developing cancer. Skin cancer (nonmelanoma) was a rare side effect reported in studies of Litfulo. Other types of cancer, such as lymphoma, breast cancer, and lung cancer, have been reported with other JAK inhibitors.

Cancer may cause different symptoms depending on the type of cancer. Examples can include:

  • a new lump or swelling
  • unusual bruising or bleeding
  • frequent infections
  • unintentional weight loss
  • cough or shortness of breath that doesn’t go away
  • skin changes, such as a new mole, changes in a mole, or a skin sore that doesn’t heal

Factors that can increase the risk of cancer when taking this drug include smoking (past or current) and having had cancer in the past.

What might help

If you’ve ever had cancer or smoked, talk with your doctor about whether Litfulo is right for you.

In many cases, skin cancer can be cured if caught early. Your doctor may recommend visiting a dermatologist regularly to check your skin while taking this drug. This is especially important for people who already have an increased risk of skin cancer.

If you have any symptoms of cancer while taking Litfulo, contact your doctor so they can determine the cause of your symptoms.

Risk of blood clots

Litfulo can increase your risk of dangerous blood clots, for example, in your lungs, legs, or eyes. Blood clots were a rare side effect reported in studies of Litfulo.

Blood clots may cause symptoms such as:

  • pain, swelling, warmth, or discoloration in your leg
  • sudden chest or upper back pain
  • shortness of breath
  • sudden change in your vision, especially in only one eye

Factors that can increase the risk of blood clots when taking this drug include being age 50 years or older, past blood clots, smoking, and obesity.

What might help

Before starting Litfulo, talk with your doctor about your age and any blood clot risk factors you may have. Your doctor will consider these factors before deciding whether this treatment option is right for you.

If you have symptoms of a blood clot, contact your doctor right away. But if your symptoms feel life threatening, call 911 or your local emergency number immediately.

If you have a blood clot, your doctor will prescribe medication to treat it. They’ll also likely recommend that you stop taking Litfulo.

Risk of cardiovascular problems

Drugs from the same group as Litfulo (JAK inhibitors) can increase the risk of cardiovascular problems in certain people who take them for rheumatoid arthritis. (Keep in mind that Litfulo is not approved to treat rheumatoid arthritis.)

Examples of these problems include heart attack and stroke. However, cardiovascular problems were rarely reported in studies of Litfulo.

Cardiovascular problems may cause symptoms such as:

  • chest pain, tightness, or pressure that may spread to your back, arm, neck, throat, or jaw
  • cold sweats
  • shortness of breath
  • dizziness or lightheadedness
  • sudden weakness or numbness in one side of your face or body
  • difficulty speaking or walking

Factors that can increase the risk of cardiovascular problems when taking this drug include:

  • being age 50 years or older
  • heart disease
  • high blood pressure
  • high cholesterol
  • diabetes
  • obesity
  • being a current or past smoker

What might help

Before starting Litfulo, talk with your doctor about your age and any cardiovascular risk factors you may have. Your doctor will take these into consideration when deciding whether Litfulo is right for you.

If you have symptoms of cardiovascular problems during Litfulo treatment, call 911 or your local emergency number right away.

If you have a heart attack or stroke, your doctor will likely recommend that you stop Litfulo treatment.

Increased liver enzymes

An increased level of liver enzymes was a rare side effect reported in studies of Litfulo. Increased liver enzymes can be a sign of liver damage or that your liver isn’t working as well as it should be.

Liver problems may cause symptoms such as:

  • nausea and vomiting
  • pain in your upper-right abdomen
  • dark-colored urine
  • bruising easily
  • jaundice (yellowing of your skin or the whites of your eyes)

What might help

Your doctor will likely order liver function tests before and during your Litfulo treatment. If you have symptoms of liver problems during treatment, tell your doctor. They may order further tests to check your liver. If Litfulo affects your liver, your doctor will likely recommend you stop taking this drug.

Allergic reaction

Like most drugs, Litfulo can cause an allergic reaction in some people. However, this side effect was rare in the drug’s 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, contact 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 Litfulo, they’ll decide whether you should continue taking 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 Litfulo, they may have you switch to a different treatment.

Keeping track of side effects

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

Below is important information you should consider before starting Litfulo.

Boxed warnings

Litfulo has boxed warnings about the risks of serious infection, cancer, blood clots, and cardiovascular problems, as well as an increased risk of death. Boxed warnings are the most serious warnings from the FDA.

To learn more about each of these risks, see the “Side effects explained” section above.

Other warnings

Litfulo can sometimes cause harmful effects in people with certain conditions. This is known as a drug-condition interaction. Other factors may also affect whether this drug is a good treatment option for you. Talk with your doctor about your health history before starting Litfulo. Be sure to tell them if any of the following factors apply to you:

  • liver problems
  • low white blood cell or platelet counts
  • past allergic reaction to Litfulo
  • pregnancy
  • breastfeeding

Alcohol and Litfulo

There are no known interactions between alcohol and Litfulo. However, if you have certain side effects with Litfulo, drinking alcohol could make them worse. Examples include headache, dizziness, and diarrhea.

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

Pregnancy and breastfeeding with Litfulo

There is limited information about the safety of Litfulo when taken during pregnancy or while breastfeeding.

Pregnancy

It’s not known whether it’s safe to take Litfulo during pregnancy. If you’re pregnant or planning to become pregnant, talk with your doctor before starting this medication.

If you take this drug while pregnant, consider signing up for the drug’s Pregnancy Exposure Registry by talking with your doctor or by calling 877-390-2940. A pregnancy registry collects information about the safety of certain drugs when taken during pregnancy.

Breastfeeding

It isn’t known whether Litfulo is safe to take while breastfeeding. The drug could possibly cause serious side effects in a child who’s breastfed.

For this reason, you should not breastfeed while taking Litfulo and for at least 14 hours after stopping treatment. If you’re breastfeeding or planning to do so, talk with your doctor about your options.

Like most drugs, Litfulo can cause a number of side effects that range from mild to serious. However, most are temporary and go away after a few days to weeks. If you have questions about side effects that Litfulo can cause, talk with your doctor.

Examples of questions you may want to ask include:

  • Do I have a higher risk of certain side effects than others?
  • Will I need any monitoring for side effects while taking Litfulo?
  • If I need to stop this medication due to side effects, will I lose hair that’s regrown?
  • Will I still have an increased risk of cancer after stopping Litfulo?

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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.