Litfulo for hair loss represents a significant advance in treating severe alopecia areata, an autoimmune condition that can cause devastating scalp and body hair loss. Litfulo (ritlecitinib), developed by Pfizer and authorised in the UK by the MHRA, is a once-daily oral capsule that works by targeting specific immune signalling pathways responsible for follicle damage. Indicated for adults and adolescents aged 12 and over with severe alopecia areata, it offers a new option where treatments have historically been limited. This article explains how Litfulo works, who it is suitable for, its safety profile, and what patients can realistically expect from treatment.

What Is Litfulo and How Does It Treat Hair Loss?

Litfulo (ritlecitinib) is a once-daily oral JAK3 and TEC kinase inhibitor that reduces the immune-mediated inflammation attacking hair follicles, thereby supporting regrowth in alopecia areata. It is authorised in the UK by the MHRA and taken as a 50 mg capsule.

Litfulo is the brand name for ritlecitinib, a targeted oral medicine developed by Pfizer. In the UK, Litfulo holds a Marketing Authorisation granted by the Medicines and Healthcare products Regulatory Agency (MHRA). In the European Union, it is authorised by the European Commission following assessment by the European Medicines Agency (EMA). It represents a notable development in dermatological therapeutics, particularly for conditions that have historically had limited treatment options.

Ritlecitinib works by selectively inhibiting two groups of enzymes: JAK3 (Janus kinase 3) and the TEC family kinases. These enzymes play a central role in the signalling pathways that drive the immune-mediated attack on hair follicles. By blocking these pathways, ritlecitinib helps to reduce the inflammatory response that contributes to follicle damage, thereby supporting hair regrowth. This mechanism of action places it within the broader class of JAK inhibitors, a group of medicines used across several immune-mediated conditions.

Litfulo is taken as a once-daily oral capsule at a dose of 50 mg, as specified in the UK Summary of Product Characteristics (SmPC). The capsules may be taken with or without food and should be swallowed whole. As with all medicines in this class, careful patient assessment — including review of contraindications, potential interactions, and individual risk factors — is essential before initiating treatment. Patients should refer to the full SmPC or discuss any questions with their prescribing specialist.

Which Types of Hair Loss Can Litfulo Help With?

Litfulo is licensed specifically for severe alopecia areata — including alopecia totalis and universalis — in adults and adolescents aged 12 and over with a SALT score of 50 or above. It is not indicated for androgenetic alopecia, telogen effluvium, or scarring alopecias.

Litfulo is specifically indicated for the treatment of severe alopecia areata in adults and adolescents aged 12 years and over. Alopecia areata is an autoimmune condition in which the body's immune system mistakenly targets hair follicles, leading to patchy or extensive hair loss on the scalp, face, and body. In its most severe forms — including alopecia totalis (complete scalp hair loss) and alopecia universalis (total body hair loss) — the condition can have a profound impact on a person's psychological wellbeing and quality of life.

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Clinical trial data from the ALLEGRO programme, which supported Litfulo's authorisation, demonstrated meaningful hair regrowth in a significant proportion of patients with severe alopecia areata. Severity is typically assessed using the Severity of Alopecia Tool (SALT) score. In the ALLEGRO trials, eligible patients generally had a SALT score of 50 or above (indicating loss of at least 50% of scalp hair); this threshold reflects the trial inclusion criteria and may also inform local NHS commissioning decisions. Patients and clinicians should note that NHS funding pathways in England are subject to NICE guidance or interim commissioning policies, which may vary; the current status of any NICE technology appraisal for ritlecitinib should be confirmed at the time of prescribing. Treatment should be initiated by a consultant dermatologist experienced in managing alopecia areata, in a secondary or tertiary care setting.

It is important to note that Litfulo is not indicated for other common forms of hair loss, such as:

• Androgenetic alopecia (male or female pattern baldness)

• Telogen effluvium (stress- or illness-related shedding)

• Scarring alopecias (e.g., lichen planopilaris)

Patients experiencing hair loss should seek a formal diagnosis from their GP or a dermatologist before considering any treatment, as the underlying cause significantly determines the most appropriate management approach.

Potential Side Effects and Safety Considerations

Common side effects include acne, headache, diarrhoea, urticaria, upper respiratory infections, and herpes zoster; class-wide risks include serious infections, MACE, VTE, and malignancy. Pre-treatment screening and regular monitoring are mandatory.

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As with all medicines, Litfulo carries a risk of side effects, and patients should be fully informed before starting treatment. In clinical trials and as listed in the UK SmPC, commonly reported adverse effects included:

• Acne or folliculitis (inflammation of hair follicles)

• Headache

• Diarrhoea

• Urticaria (hives or skin rash)

• Upper respiratory tract infections

• Herpes zoster (shingles) — patients should ensure their varicella-zoster immunity status is assessed before starting treatment, and vaccination should be considered where appropriate

Blood test abnormalities (such as changes in blood counts or liver enzymes) have been observed with JAK inhibitors as a class and may be monitored during treatment; patients should attend all scheduled blood test appointments.

Because ritlecitinib modulates immune signalling pathways, there is an increased risk of infections, including serious or opportunistic infections. Litfulo should not be started in patients with an active serious infection. Pre-treatment screening should include testing for tuberculosis (TB), viral hepatitis (B and C), and assessment of varicella-zoster immunity. Live vaccines should be avoided during treatment, and patients should ensure their vaccinations are up to date before beginning therapy. If a serious infection develops during treatment, the prescribing specialist should be contacted promptly and interruption of therapy considered.

The JAK inhibitor class as a whole has been associated with an increased risk of major adverse cardiovascular events (MACE), venous thromboembolism (VTE), and malignancy, particularly in older patients with existing cardiovascular risk factors. The MHRA has issued Drug Safety Updates on these class-wide risks. Prescribers are advised to assess individual risk carefully, taking into account personal and family history of cardiovascular disease, thromboembolism, and malignancy. Litfulo should be used with caution in patients with relevant risk factors, and the benefit–risk balance should be reviewed regularly.

Drug interactions: Ritlecitinib is metabolised via CYP3A pathways. Concomitant use of strong CYP3A inhibitors or inducers may affect ritlecitinib exposure; prescribers should consult the SmPC for full interaction guidance. Litfulo should not be used in combination with other potent immunosuppressants or biological therapies without specialist review.

Patients should contact their GP or specialist promptly if they experience:

• Signs of serious infection (high fever, persistent cough, difficulty breathing)

• Symptoms of shingles (painful rash, blistering)

• Unexplained bruising or bleeding

• Chest pain or leg swelling

• Any new or unusual symptoms

Litfulo is not recommended during pregnancy or breastfeeding. Women of childbearing potential should use effective contraception during treatment and for a period after the last dose, as specified in the UK SmPC. Patients should discuss contraception requirements with their prescribing specialist before starting treatment.

Reporting side effects: Patients and healthcare professionals are encouraged to report any suspected side effects via the MHRA Yellow Card scheme at yellowcard.mhra.gov.uk or via the Yellow Card app. Reporting helps the MHRA monitor the ongoing safety of medicines in the UK.

What to Expect During and After Treatment

Hair regrowth with Litfulo is gradual, with some patients seeing improvement within three to six months; however, alopecia areata may relapse after stopping treatment. Long-term therapy and regular specialist review are typically required for sustained benefit.

Starting Litfulo requires a thorough assessment by a consultant dermatologist, who will review the patient's medical history, conduct baseline investigations, and confirm eligibility. Baseline blood tests — including a full blood count and liver function tests — are typically performed before treatment begins and monitored periodically thereafter, in line with the UK SmPC. Patients should discuss the specific tests required and the recommended monitoring schedule with their specialist. This ongoing monitoring is an important part of ensuring the medicine remains safe and appropriate for each individual.

Hair regrowth with Litfulo is generally a gradual process. In the ALLEGRO clinical studies, some patients began to see visible improvement within three to six months, though the full extent of regrowth may take longer to become apparent. Response rates varied between individuals, and not all patients will achieve the same degree of regrowth. If there is no meaningful response after an adequate trial period — typically assessed at around six months, in line with the evidence from the ALLEGRO programme and SmPC guidance — the treating specialist may recommend discontinuing treatment and exploring alternative options. Specific laboratory thresholds that may require dose interruption or discontinuation are detailed in the SmPC and should be reviewed by the prescribing team.

For those who do respond well, an important consideration is what happens if treatment is stopped. Evidence from the ALLEGRO programme indicates that alopecia areata is a chronic, relapsing condition, and hair loss may recur after discontinuation of ritlecitinib. Long-term treatment may therefore be necessary for sustained benefit, and this should be discussed openly between the patient and their specialist, with the ongoing benefits weighed carefully against potential risks at regular review appointments.

Beyond the physical aspects of treatment, the psychological impact of alopecia areata should not be underestimated. Patients are encouraged to access support through organisations such as Alopecia UK, and the NHS provides patient information on alopecia areata and available support services. Psychological support or counselling may be beneficial alongside medical treatment. A holistic approach — combining effective pharmacological management with emotional and practical support — is considered best practice in the care of patients living with severe alopecia areata.

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