Topical vitamin D preparations contain synthetic vitamin D analogues such as calcipotriol, calcitriol, and tacalcitol, formulated as creams, ointments, gels, or scalp solutions. Licensed by the MHRA primarily for treating plaque psoriasis, these dermatological treatments work locally on the skin to regulate abnormal cell growth and reduce inflammation. Unlike oral vitamin D supplements used for deficiency, topical formulations are not intended to address systemic vitamin D levels. NICE recommends topical vitamin D analogues as first-line treatment for mild-to-moderate plaque psoriasis affecting the trunk and limbs. This article explores how topical vitamin D works, which conditions it treats, safe application techniques, and important precautions for UK patients.

What Is Topical Vitamin D and How Does It Work?

Topical vitamin D refers to a class of dermatological preparations containing vitamin D analogues, most commonly calcipotriol, calcitriol and tacalcitol. These synthetic derivatives of vitamin D₃ are formulated as creams, ointments, gels, or scalp solutions and are licensed by the MHRA for the treatment of certain skin conditions, particularly psoriasis. Unlike oral vitamin D supplements used to treat deficiency, topical formulations work locally on the skin and are not intended to address systemic vitamin D levels.

The mechanism of action centres on the regulation of skin cell proliferation and differentiation. In conditions like psoriasis, keratinocytes (the predominant cells in the outer layer of skin) multiply excessively, leading to the characteristic thickened, scaly plaques. Topical vitamin D analogues bind to vitamin D receptors within these cells, normalising the rate of cell turnover and reducing the excessive scaling and inflammation. They also modulate immune responses in the skin, decreasing the activity of T-lymphocytes and the production of pro-inflammatory cytokines that contribute to plaque formation.

Calcipotriol is often combined with a topical corticosteroid such as betamethasone dipropionate in fixed-dose combination products. This dual approach enhances efficacy: the corticosteroid provides rapid anti-inflammatory relief, whilst the vitamin D analogue offers longer-term control of abnormal skin cell growth. According to NICE guidance (CG153), topical vitamin D analogues are recommended for mild-to-moderate plaque psoriasis in adults, with specific recommendations varying by body site. For trunk and limbs, a vitamin D analogue applied twice daily or a vitamin D/corticosteroid combination once daily is typically recommended. These preparations are available on prescription and should be used under medical supervision to ensure appropriate application and monitoring.

Conditions Treated with Topical Vitamin D

The primary indication for topical vitamin D analogues is plaque psoriasis, a chronic inflammatory skin condition affecting approximately 2–3% of the UK population according to NHS estimates. Psoriasis manifests as well-demarcated, erythematous plaques covered with silvery-white scales, commonly appearing on the elbows, knees, scalp, and lower back. NICE recommends topical vitamin D or vitamin D/corticosteroid combinations as first-line treatment for adults with trunk or limb psoriasis, particularly when the affected body surface area is limited.

Topical calcipotriol is also used for scalp psoriasis, where it is formulated as a solution or foam to facilitate application through hair. Scalp involvement can be particularly troublesome for patients due to visible scaling and associated social stigma. The vitamin D analogue helps reduce plaque thickness and scaling whilst being cosmetically more acceptable than some tar-based preparations.

It is important to note that vitamin D analogues are generally not recommended for use on the face, flexures or genital areas due to increased risk of irritation. These areas typically require different treatment approaches as outlined in NICE guidance.

In certain cases, dermatologists may prescribe topical vitamin D analogues off-label for other hyperproliferative or inflammatory skin disorders, though these uses should be specialist-led only and are not routinely recommended. Some specialists have explored their use in conditions such as vitiligo, ichthyosis, and palmoplantar keratoderma, but these applications lack the robust evidence base supporting their use in psoriasis.

Patients should be referred to a specialist if their psoriasis fails to respond adequately after 4-8 weeks of treatment, affects more than 10% of body surface area, significantly impacts quality of life, involves the nails, affects genital areas, or if psoriatic arthritis is suspected.

It is important to note that topical vitamin D preparations are not indicated for treating vitamin D deficiency, which requires oral supplementation. Patients with confirmed deficiency should follow guidance from their GP regarding appropriate oral vitamin D₃ (colecalciferol) dosing, typically in accordance with local formulary recommendations or NHS guidance.

How to Use Topical Vitamin D Safely

Proper application technique is essential to maximise therapeutic benefit whilst minimising the risk of adverse effects. Topical vitamin D analogues should be applied thinly and evenly to affected areas only, typically once or twice daily as directed by the prescribing clinician or as stated in the patient information leaflet. The 'fingertip unit' (FTU) method can help patients gauge appropriate quantities: one FTU (the amount squeezed from fingertip to first crease) covers an area roughly twice the size of an adult's flat hand.

Key safety considerations include:

• Maximum weekly dose limits: Product-specific weekly maxima must not be exceeded to prevent hypercalcaemia. These include:
• Calcipotriol (Dovonex/Daivonex): 100g/week for adults
• Calcipotriol scalp solution: 60ml/week
• Calcipotriol/betamethasone (Dovobet) gel/ointment: 100g/week
• Calcipotriol/betamethasone (Enstilar) foam: 60g/week

• For children (where licensed), lower weekly maxima apply based on age and weight

• Avoid sensitive areas: Do not apply to the face, eyes, or mucous membranes unless specifically directed by a specialist, as these areas are more prone to irritation.

• Wash hands after application: Unless treating the hands themselves, wash thoroughly after use to prevent accidental transfer to sensitive areas.

• Timing with other treatments: When using combination therapy, apply different topical treatments at separate times (e.g., morning and evening) unless using a fixed-combination product.

• Avoid salicylic acid: Do not use salicylic acid-containing preparations on the same area as calcipotriol, as salicylic acid can inactivate it.

• UV exposure: Limit excessive sun exposure to treated areas and coordinate with phototherapy if prescribed, following clinician guidance.

Patients should apply the preparation to clean, dry skin. If using emollients (moisturisers), these should be applied first and allowed to absorb for at least 30 minutes before applying the vitamin D analogue, to prevent dilution and ensure optimal penetration. Conversely, if applying a topical corticosteroid separately, the vitamin D preparation is typically applied at a different time of day.

When to contact your GP: Patients should seek medical advice if they experience severe skin irritation, facial swelling, signs of infection in treated areas, or symptoms potentially indicating hypercalcaemia (excessive thirst, frequent urination, nausea, or confusion). In line with NICE recommendations, an initial review should occur after approximately 4 weeks to assess response and adherence, with further follow-up as clinically indicated.

Side Effects and Precautions

Topical vitamin D analogues are generally well-tolerated, but patients should be aware of potential adverse effects. The most common side effects are local skin reactions, which include:

• Mild irritation, itching, or burning at application sites, usually transient and resolving with continued use

• Erythema (redness) or dermatitis, particularly if applied to thin or sensitive skin

• Dry skin or peeling, which can often be managed with regular emollient use

Less commonly, patients may experience worsening of psoriasis. Rarely, excessive use beyond recommended doses can lead to hypercalcaemia (elevated blood calcium levels), presenting with symptoms such as nausea, vomiting, constipation, excessive thirst, or confusion. This risk is higher in patients applying large quantities over extensive body surface areas or those with pre-existing disorders of calcium metabolism.

Important precautions include:

• Contraindications: Do not use in patients with known hypercalcaemia or disorders of calcium metabolism.

• Pregnancy and breastfeeding: Topical vitamin D analogues should be used during pregnancy only if the benefit clearly outweighs the risk, as systemic absorption may occur. The amount excreted in breast milk is likely minimal, but avoid application to the breast area during breastfeeding. Pregnant or breastfeeding women should discuss treatment options with their GP or dermatologist.

• Renal impairment: Patients with severe kidney disease require careful monitoring due to altered calcium homeostasis.

• Drug interactions: Avoid concurrent use with salicylic acid-containing preparations on the same area, as this can inactivate calcipotriol. Patients taking calcium supplements or thiazide diuretics (which can raise calcium levels) should inform their healthcare provider.

• Children: Calcipotriol is licensed for use in children over 6 years, but with lower weekly maximum doses based on age and weight. Calcitriol is not routinely used in children. Paediatric use should be supervised by a healthcare professional.

• Monitoring: Consider serum calcium monitoring if treating large body surface areas or using near-maximal weekly doses.

Patients should store preparations away from heat and light, and check expiry dates regularly. If irritation persists or worsens despite correct use, a review with the prescribing clinician is warranted to consider alternative formulations or adjunctive emollient therapy.

Any suspected side effects should be reported to the MHRA Yellow Card Scheme (yellowcard.mhra.gov.uk).

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