Litfulo (Ritlecitinib)

What Is Litfulo and What Is It Used For?

Litfulo (ritlecitinib) is a prescription medicine used to treat severe alopecia areata in adults and adolescents from 12 years of age. It is a Janus kinase (JAK) inhibitor that works by reducing the activity of specific enzymes involved in the autoimmune attack on hair follicles, enabling hair to regrow.

Alopecia areata is an autoimmune disease in which the body's own immune system mistakenly attacks hair follicles, the tiny structures in the skin from which hair grows. This immune attack causes inflammation around the hair follicles, leading to hair loss on the scalp, face (eyebrows, eyelashes, and beard), and sometimes on other parts of the body. The condition affects approximately 2% of the global population at some point in their lifetime, and severe forms can have a profound impact on quality of life, self-esteem, and psychological well-being.

Litfulo contains the active substance ritlecitinib, which belongs to a class of medicines known as Janus kinase (JAK) inhibitors. Ritlecitinib is unique among JAK inhibitors because it selectively and irreversibly blocks two specific groups of enzymes: JAK3 and the TEC family of kinases (including TEC, BTK, BMX, ITK, and TXK). JAK3 signals exclusively through gamma-common (γc) cytokine receptors, which are critical for the development and function of certain immune cells. By targeting these pathways, ritlecitinib reduces the activity of natural killer (NK) cells and CD8+ cytotoxic T lymphocytes – the immune cells primarily responsible for attacking hair follicles in alopecia areata.

By dampening this abnormal immune response, Litfulo reduces the inflammation surrounding hair follicles and creates an environment that allows hair to regrow. In pivotal clinical trials (ALLEGRO-2b/3), patients with severe alopecia areata who took Litfulo 50 mg daily showed statistically significant and clinically meaningful hair regrowth compared to placebo. After 24 weeks of treatment, approximately 23% of patients achieved a Severity of Alopecia Tool (SALT) score of 20 or less (meaning 80% or more scalp hair coverage), compared to only 1.6% of patients on placebo. Improvements continued through week 48, with more patients achieving substantial regrowth over time.

Unlike some topical treatments for alopecia areata, Litfulo addresses the underlying immune dysregulation systemically. This makes it particularly suitable for patients with extensive hair loss who have not responded adequately to other therapies. The European Medicines Agency (EMA) approved Litfulo in 2023, and the U.S. Food and Drug Administration (FDA) granted approval for ritlecitinib for severe alopecia areata in adults, making it one of the first oral treatments specifically licensed for this indication.

What Should You Know Before Taking Litfulo?

Before starting Litfulo, inform your doctor about all medical conditions, especially active infections, liver problems, history of blood clots, cancer, or if you are pregnant or breastfeeding. Litfulo has several important contraindications and requires monitoring blood tests before and during treatment.

Contraindications

You should not take Litfulo if any of the following apply to you:

• Allergy to ritlecitinib or any of the other ingredients in Litfulo (listed in the contents section below) – symptoms may include skin rash, itching, swelling, or difficulty breathing
• Active serious infection, including tuberculosis (TB) – Litfulo reduces your immune system's ability to fight infections and could worsen an existing serious infection or make it life-threatening
• Severe liver problems (severe hepatic impairment) – impaired liver function can lead to dangerous drug accumulation in the body
• Pregnancy or breastfeeding – Litfulo may harm the developing foetus and it is unknown whether it passes into breast milk (see the Pregnancy and Breastfeeding section below)

Warnings and Precautions

Talk to your doctor or pharmacist before and during treatment with Litfulo if you have any of the following conditions or concerns:

• Current infection or recurrent infections: Litfulo can impair your body's ability to fight infections. Signs of infection include fever, sweating, chills, muscle aches, cough, shortness of breath, blood in sputum, weight loss, diarrhoea, stomach pain, burning sensation when urinating, urinating more often than usual, or feeling very tired. Tell your doctor immediately if you develop any of these symptoms during treatment.
• Diabetes or age over 65 years: You may have an increased risk of infections while taking Litfulo. Your doctor may monitor you more closely.
• Tuberculosis (TB): If you have, have had, or have been in close contact with someone who has TB, or if you live in or travel to areas where TB is common, your doctor will test you for TB before starting Litfulo and may retest during treatment.
• Herpes zoster (shingles): If you have ever had chickenpox or shingles, Litfulo may allow the virus to reactivate. Tell your doctor immediately if you develop a painful skin rash with blisters, as this could be a sign of shingles. Your doctor may recommend vaccination against shingles before starting treatment.
• Hepatitis B or C: Your doctor will test you for hepatitis before starting Litfulo and may retest during treatment, as JAK inhibitors can affect viral hepatitis.
• Cancer: It is not yet clear whether Litfulo increases the risk of cancer. Your doctor will discuss whether treatment is appropriate for you and whether regular check-ups, including skin examinations, are needed during treatment.
• Blood clots: If you have had deep vein thrombosis (DVT), pulmonary embolism (PE), or retinal vein occlusion, tell your doctor before starting Litfulo. Seek immediate medical attention if you develop leg pain and swelling, chest pain, or sudden breathlessness.
• Cardiovascular events: If you have had a heart attack or retinal artery occlusion, inform your doctor. Seek emergency care if you experience sudden vision changes (blurred vision, partial or complete vision loss), chest pain, or breathlessness.
• Vaccinations: Live vaccines (such as MMR, varicella, or oral polio) should not be given during Litfulo treatment. Ask your doctor whether you need any vaccinations, including shingles vaccination, before starting treatment.
• Neurological symptoms: If you develop unexplained neurological symptoms while taking Litfulo, contact your doctor immediately. Your doctor will decide whether treatment should be discontinued.

Pregnancy and Breastfeeding

Litfulo must not be used during pregnancy. The medication may cause harm to a developing foetus. If you are a woman of childbearing potential, you must use effective contraception during treatment with Litfulo and for at least one month after the last dose. Your doctor can advise on suitable contraceptive methods.

If you become pregnant or suspect you may be pregnant while taking Litfulo, stop taking the medication and contact your doctor immediately. Your doctor will discuss the risks and help you make informed decisions about your care.

Litfulo must not be used during breastfeeding. It is not known whether ritlecitinib passes into breast milk or whether it could affect a breastfed child. You and your doctor should decide together whether you should breastfeed or use this medication – you should not do both.

Fertility

It is not currently known whether Litfulo affects fertility in women or men. If you are planning to have children, discuss this with your doctor before starting treatment.

Driving and Operating Machinery

Litfulo has no or negligible effect on the ability to drive and use machines. However, dizziness is a common side effect. If you experience dizziness while taking Litfulo, you should avoid driving or using machinery until the symptom has resolved.

Use in Children

Litfulo is approved for use in adolescents aged 12 years and older with severe alopecia areata. The dose is the same as for adults: 50 mg once daily. Litfulo has not been studied and is not approved for use in children under 12 years of age, as the safety and efficacy in this age group have not been established.

How Does Litfulo Interact with Other Drugs?

Litfulo can increase the blood levels of certain medications by inhibiting liver enzymes involved in drug metabolism. Always tell your doctor about all medicines you are taking, including over-the-counter medications, herbal supplements, and vitamins, before starting Litfulo.

Ritlecitinib can affect the way certain other medicines work in your body, and conversely, some medicines may affect how ritlecitinib works. This is because ritlecitinib inhibits specific enzymes in the liver that are responsible for breaking down (metabolising) other drugs. When these enzymes are inhibited, the blood levels of other medications may increase, which can enhance both their therapeutic effects and their side effects.

You should be especially careful and inform your doctor or pharmacist before taking Litfulo if you are using any of the following types of medication:

Major Interactions

The following medications may have their blood levels significantly increased by Litfulo. Your doctor may need to adjust your dose or monitor you more closely:

Other Notable Interactions

The following medications may also be affected when taken with Litfulo:

• Theophylline (used for asthma) – blood levels may increase, requiring dose monitoring
• Tizanidine (used for muscle spasms) – blood levels may increase, leading to excessive muscle relaxation or low blood pressure
• Pirfenidone (used for idiopathic pulmonary fibrosis) – blood levels may increase, potentially increasing side effects

This is not a complete list of all possible drug interactions. Always inform your healthcare provider about every medication you are taking – including over-the-counter medicines, vitamins, and herbal supplements – so they can check for potential interactions before prescribing Litfulo.

What Is the Correct Dosage of Litfulo?

The recommended dose of Litfulo is 50 mg once daily, taken as a single capsule by mouth. The capsule should be swallowed whole with water and can be taken with or without food. The same dose applies to adults and adolescents aged 12 years and older.

Always take Litfulo exactly as your doctor has told you. Do not change your dose or stop taking Litfulo without first talking to your doctor. Consistent daily use is important for achieving and maintaining hair regrowth.

Adults and Adolescents (12 Years and Older)

Children Under 12 Years

Elderly Patients

No dose adjustment is required for elderly patients. However, patients over 65 years of age may have an increased risk of infections during treatment. Your doctor will carefully consider whether Litfulo is appropriate for you and will monitor you closely during treatment. Clinical experience with Litfulo in patients over 65 is limited.

Patients with Liver or Kidney Impairment

Litfulo is contraindicated in patients with severe liver impairment. For patients with mild to moderate liver impairment, no dose adjustment is required, but your doctor may monitor you more closely. No dose adjustment is needed for patients with kidney impairment, as the kidneys play a minor role in the elimination of ritlecitinib.

Missed Dose

If you forget to take a dose of Litfulo, follow these guidelines:

• If more than 8 hours remain until your next scheduled dose: take the missed dose as soon as you remember
• If less than 8 hours remain until your next dose: skip the missed dose and take your next dose at the usual time
• Never take a double dose to make up for a forgotten capsule

Overdose

If you have taken more Litfulo than prescribed, contact your doctor immediately. An overdose may increase the risk and severity of side effects described in this article. There is no specific antidote for ritlecitinib overdose. Treatment is supportive and symptomatic.

Stopping Treatment

Do not stop taking Litfulo without discussing it with your doctor first. If treatment is discontinued, the underlying autoimmune process may resume, potentially leading to renewed hair loss. In clinical studies, short treatment breaks of up to 6 weeks were associated with a low risk of scalp hair loss. Longer interruptions may result in a return of alopecia areata symptoms.

What Are the Side Effects of Litfulo?

Like all medicines, Litfulo can cause side effects, although not everyone experiences them. The most common side effects include upper respiratory infections, diarrhoea, dizziness, acne, and rash. Serious side effects include herpes zoster (shingles) and urticaria (hives), which require prompt medical attention.

Clinical trials have shown that Litfulo is generally well tolerated. Most side effects are mild to moderate in severity and manageable with appropriate medical care. However, because Litfulo affects the immune system, it is important to be aware of potential side effects and to report any unusual symptoms to your doctor promptly.

Long-Term Safety Considerations

Because Litfulo belongs to the JAK inhibitor class, there are theoretical risks that are monitored as a class effect, even though they have not been specifically confirmed for ritlecitinib in clinical trials for alopecia areata. These include:

• Increased infection risk: By suppressing parts of the immune system, JAK inhibitors may increase susceptibility to bacterial, viral, and fungal infections. Patients should practise good hygiene and report any signs of infection promptly.
• Venous thromboembolism: Blood clots in the legs (deep vein thrombosis) or lungs (pulmonary embolism) have been reported with other JAK inhibitors. Seek immediate medical attention if you develop leg swelling, pain, chest pain, or sudden breathlessness.
• Malignancy: The long-term cancer risk with Litfulo is not yet fully characterised. Your doctor may recommend regular skin examinations during treatment.
• Cardiovascular events: Major adverse cardiovascular events (MACE) have been reported with other JAK inhibitors in older populations with cardiovascular risk factors.

It is important to keep all scheduled follow-up appointments with your doctor during Litfulo treatment. Blood tests before and approximately 4 weeks after starting treatment help detect any changes in blood cell counts or liver function early. Your doctor will advise on the frequency of ongoing monitoring based on your individual risk profile.

How Should You Store Litfulo?

Store Litfulo out of the sight and reach of children. Keep it in the original packaging to protect from light. No special temperature requirements apply. Do not use after the expiry date printed on the carton, jar, or blister.

Proper storage of Litfulo helps ensure the medication remains effective and safe throughout its shelf life. Follow these guidelines:

• Keep out of reach and sight of children – store the medication in a secure location where children cannot access it
• Store in original packaging – keep the capsules in the original container or blister pack to protect them from light
• No special temperature requirements – store at normal room temperature
• Check the expiry date – do not use Litfulo after the date marked "EXP" on the carton, jar, or blister. The expiry date refers to the last day of that month
• Do not swallow the desiccant – the bottle packaging contains a silica gel desiccant to keep the capsules dry. This desiccant must not be swallowed
• Disposal – do not throw away unused medicines via wastewater or household waste. Ask your pharmacist about proper disposal of medicines you no longer use. This helps protect the environment

What Does Litfulo Contain?

Each Litfulo hard capsule contains ritlecitinib tosylate equivalent to 50 mg of ritlecitinib as the active ingredient, along with several inactive excipients including lactose monohydrate.

Active Ingredient

Each hard capsule contains ritlecitinib tosylate, equivalent to 50 mg ritlecitinib. Ritlecitinib is the pharmacologically active component responsible for the therapeutic effects of Litfulo.

Inactive Ingredients (Excipients)

The inactive ingredients help with the manufacturing, stability, and delivery of the medicine:

• Capsule contents: Microcrystalline cellulose, lactose monohydrate, crospovidone, glycerol dibehenate
• Capsule shell: Hypromellose (E464), titanium dioxide (E171), yellow iron oxide (E172), brilliant blue FCF (E133)
• Printing ink: Shellac, propylene glycol, concentrated ammonia solution, black iron oxide (E172), potassium hydroxide

Appearance and Packaging

Litfulo 50 mg hard capsules are opaque with a yellow body and a blue cap, approximately 16 mm long and 6 mm wide, with "RCB 50" printed in black on the body and "Pfizer" printed in black on the cap.

The capsules are available in:

• HDPE plastic jars with polypropylene plastic lids containing 28 hard capsules (jar includes silica gel desiccant)
• OPA/Al/PVC/Al blister packs containing 30 or 90 hard capsules

Not all pack sizes may be marketed in your country.

Frequently Asked Questions About Litfulo

References

Editorial Team