Pronunciation: RIT-le-SYE-ti-nib
Generic name: ritlecitinib
Brand name: Litfulo
Dosage form: oral capsule (50 mg)
Drug class: Selective immunosuppressants

Medically reviewed by Carmen Pope, BPharm. Last updated on Jul 4, 2025.

What is ritlecitinib?

Ritlecitinib is used to treat severe alopecia areata in adults and adolescents aged 12 and older. The brand name is Litfulo. It is a capsule that is taken 1 time a day.

In alopecia areata, immune cells attack hair follicles, causing hair loss. Litfulo is thought to work by binding to specific proteins within immune cells, called Janus kinase 3 (JAK3) and TEC kinases, blocking their signals. This reduces the number of cells attacking the hair follicles and decreases inflammation, reducing hair loss.

Ritlecitinib was approved on June 23, 2023, under the brand name Litfulo (Pfizer Inc.). There is no generic. Approval was based on the results of the ALLEGRO (NCT03732807) phase 2b/3 randomized clinical trial, which reported:

• 23% of people experience significant hair regrowth that covered 80% or more of their scalp in just under 6 months (vs. 1.6% on placebo).
• 13.4% saw 90% or more scalp hair coverage (vs. 1.5% on placebo).

Side effects

The most common side effects of ritlecitinib are:

• acne
• atopic dermatitis
• diarrhea
• dizziness
• folliculitis
• fever
• headache
• increases in laboratory values of creatine phosphokinase and decreases in red blood cell counts
• mouth ulcers
• rash
• urticaria.

Serious side effects and warnings

Ritlecitinib carries a Boxed warning for serious infections, mortality, malignancy, major adverse cardiovascular events, and thrombosis.

Increased risk of serious infections. Ritlecitinib can lower your ability to fight infections because it affects your immune system. Serious, sometimes fatal, infections have occurred in people taking ritlecitinib or similar medicines, such as tuberculosis (TB), and many different types of bacterial, fungal, or viral infections. Your healthcare provider should test you for TB before starting treatment and monitor you for TB during treatment. You may be at a higher risk of developing shingles (herpes zoster). Do not start taking ritlecitinib if you have an infection unless your healthcare provider tells you it is okay. Tell your healthcare provider right away if you have the following signs or symptoms of an infection:

• cough or shortness of breath
• diarrhea or stomach pain
• burning when you urinate or urinating more often than usual
• feeling very tired
• fever, sweating, or chills
• muscle aches
• blood in your phlegm
• weight loss
• warm, red, or painful skin or sores on your body.

Increased risk of death in people 50 years of age and older who have at least 1 heart disease (cardiovascular) risk factor and are taking a medicine in the class of medicines called Janus kinase (JAK) inhibitors. Increased risk of death in people 50 years of age and older who have at least 1 heart disease (cardiovascular) risk factor and are taking a medicine in the class of medicines called Janus kinase (JAK) inhibitors. Ritlecitinib is a kinase inhibitor medicine.

Increased risk of malignancy (cancer). Malignancies have occurred in patients treated with ritlecitinib, including increased rates of skin cancers, lymphomas, and lung cancer, especially in current or past smokers. Follow your healthcare provider’s advice about cancer screenings during treatment.

Increased risk of major cardiovascular events (Boxed warning). People taking ritlecitinib who are 50 years of age and older with at least 1 heart disease (cardiovascular) risk factor, especially current or past smokers, have an increased risk of cardiovascular events such as heart attack, stroke, or death. Get emergency help right away if you have any symptoms of a heart attack or stroke while using ritlecitinib, including:

• • discomfort in your chest that lasts for more than a few minutes, or that goes away and comes back
  • severe tightness, pain, pressure, or heaviness in your chest, throat, neck, or jaw
  • pain or discomfort in your arms, back, neck, jaw, or stomach
  • shortness of breath with or without chest discomfort
  • breaking out in a cold sweat
  • nausea or vomiting
  • feeling lightheaded
  • weakness in one part or on one side of your body
  • slurred speech.

Thrombosis (blood clots). Blood clots have also occurred in patients treated with ritlecitinib and may be life-threatening. The risk is higher in people who are 50 years of age and older with at least 1 heart disease (cardiovascular) risk factor. These could happen in the veins of your legs (deep vein thrombosis, DVT), lungs (pulmonary embolism, PE), or eyes. Tell your healthcare provider if you have had blood clots in the past. Stop taking ritlecitinib and get medical help right away if you have any signs and symptoms of blood clots during treatment, such as:

• • sudden, unexplained chest or upper back pain
  • swelling, pain, or tenderness in one or both legs
  • shortness of breath or difficulty breathing
  • changes in vision, especially in one eye only.

Other serious side effects that can occur with ritlecitinib include:

• Allergic reactions, some of which may be severe, such as anaphylaxis. Stop taking it and get emergency medical help right away if you have symptoms of an allergic reaction, including:
  • hives
  • rash
  • trouble breathing
  • feeling faint or dizzy
  • swelling of your lips, tongue, or throat.
• Changes in certain laboratory test results. Your healthcare provider should do blood tests before you start taking Litfulo and during treatment to check for the following:
  • low lymphocyte count. Lymphocytes are white blood cells that help the body fight off infections
  • low platelet counts. Platelets help form clots and stop or prevent bleeding
  • elevated liver enzymes. Liver enzymes help to tell if your liver is functioning normally. Elevated liver enzymes may indicate that your healthcare provider needs to do additional tests on your liver
  • increased creatine phosphokinase (CPK). Increased CPK levels in the blood are common with ritlecitinib and can also be severe.

Ritlecitinib is not recommended in people with severe liver disease.

The safety of ritlecitinib in children under 12 years of age has not been established.

These are not all the possible side effects of ritlecitinib. Call your doctor for medical advice about side effects. You may report side effects to the FDA at 1-800-FDA-1088. You may also report side effects to Pfizer at 1-800-438-1985.

Related/similar drugs

Before taking this medicine

Do not use ritlecitinib if you:

• have severe liver disease
• are allergic to ritlecitinib, ritlecitinib, or any inactive ingredients in the capsule.

Before starting this medicine, tell your healthcare provider about all your medical conditions, including if you:

• have an infection that has not gone away or that keeps coming back. Symptoms of an infection include fever, chills, muscle aches, cough, trouble breathing, skin sores, diarrhea, or painful urination
• are being treated for an infection
• live or have lived or have traveled to certain parts of the country (such as the Ohio and Mississippi River valleys and the Southwest) where there is an increased chance of getting certain kinds of fungal infections. These infections may happen or become more severe if you use ritlecitinib.
• have had hepatitis B or hepatitis C, or liver disease
• have TB or have been in close contact with someone with TB
• have had shingles (herpes zoster)
• have diabetes, chronic lung disease, HIV, or a weak immune system
• have any type of cancer
• have heart problems or have had a heart attack, stroke, or blood clot
• have ever smoked
• are scheduled to receive a vaccine
• are pregnant or intend to become pregnant
• are breastfeeding.

Your healthcare provider will do blood tests before you start taking ritlecitinib and during treatment. Your healthcare provider may stop treatment for a period if needed because of changes in these blood test results.

Pregnancy

Tell your doctor if you are pregnant or plan to become pregnant. It is not known if this medicine will harm an unborn baby. There is a pregnancy registry for people who take ritlecitinib during pregnancy. Report pregnancies to Pfizer Inc. at 1-877-390-2940.

Breastfeeding

Tell your doctor if you are breastfeeding or plan to breastfeed. Breastfeeding is not recommended during treatment with ritlecitinib and for approximately 14 hours after the last dose.

How do I take ritlecitinib?

Take ritlecitinib exactly as your healthcare provider tells you to take it. Do not take more or less than prescribed.

• Ritlecitinib is taken 1 time a day. 
• Take with or without food.
• Swallow the capsules whole. Do not crush, split, or chew.

Dosing information

Dose of ritlecitinib for alopecia areata (adults and children 12+):

• 50 mg (one capsule) once daily.

What happens if I miss a dose?

Take the missed dose as soon as you remember. Skip the missed dose if it is less than 8 hours before the next dose. Do not use extra medicine to make up for the missed dose.

Temporary treatment interruptions for less than 6 weeks are not expected to result in significant loss of regrown scalp hair.

What happens if I overdose?

Ritlecitinib is not expected to be toxic in overdose. Seek emergency medical attention or call the Poison Help line at 1-800-222-1222.

What should I avoid while using ritlecitinib?

Avoid receiving a "live" vaccine. Live vaccines include measles, mumps, rubella (MMR), rotavirus, typhoid, yellow fever, varicella (chickenpox), and zoster (shingles).

What other drugs will affect ritlecitinib?

Tell your doctor about all your other medicines, especially:

• CYP3A substrates (such as acetaminophen, codeine, ciclosporin, diazepam, and erythromycin)
• CYP3A inducers (such as rifampicin)
• CYP1A2 substrates, such as caffeine, clozapine, tacrine, propranolol, and mexiletine.

Should not be used in combination with other JAK inhibitors, biologic immunomodulators, cyclosporine, or other potent immunosuppressants.

This list is not complete. Other drugs may affect ritlecitinib, including prescription and over-the-counter medicines, vitamins, and herbal products. Not all possible drug interactions are listed here.

Ingredients

Ritlecitinib is only available as Litfulo.

Active: ritlecitinib 50 mg (equivalent to 80.13 mg ritlecitinib tosylate)

Inactive: crospovidone, glyceryl dibehenate, lactose monohydrate, microcrystalline cellulose, and hypromellose (HPMC) capsule shells. The yellow/blue, opaque capsule shells contain brilliant blue FCF – FD&C Blue, hypromellose, titanium dioxide, and yellow iron oxide.

Available as 50 mg capsules. Each bottle contains 28 capsules.

Storage

Store at room temperature in the original container.

The ritlecitinib bottle has a child-resistant closure and contains a canister with a drying agent (desiccant). Do not eat the desiccant.

Keep out of the reach of children.

Manufacturer

Ritlecitinib is manufactured by Pfizer Inc., under the brand Litfulo. Pfizer’s headquarters are in New York City.

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Further information

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