Two topical calcineurin inhibitors are available on prescription in the UK, and neither is a steroid: tacrolimus ointment, sold as Protopic, and pimecrolimus cream, sold as Elidel (British Association of Dermatologists, Topical calcineurin inhibitors). Both are licensed specifically for atopic dermatitis, and neither carries the skin-thinning risk that limits how long a potent steroid can stay on thin skin. The NHS atopic eczema treatment page names emollients and topical corticosteroids and does not name either drug (NHS, Atopic eczema treatment).
They are second-line by design. The NICE technology appraisal covering both states they are "not recommended for the treatment of mild atopic eczema or as first-line treatments" (NICE TA82, 2004). So the useful question is not whether you can ask for one instead of a steroid, but whether your eczema, its severity and the part of the body it sits on match the situation the licences and the guidance describe.
What a calcineurin inhibitor does
Calcineurin is a calcium-dependent enzyme inside T cells, one link in the chain that ends with a cell producing inflammatory signals. Tacrolimus binds a protein called FKBP12, and that complex inhibits "calcium-dependent signal transduction pathways in T cells, thereby preventing the transcription and synthesis of IL-2, IL-3, IL-4, IL-5" and other cytokines (Protopic SmPC). Pimecrolimus is an ascomycin macrolactam derivative that "inhibits the calcium-dependent phosphatase calcineurin" and "blocks the synthesis of inflammatory cytokines in T cells" (Elidel SmPC). Both interrupt the inflammatory signal at the point where the T cell would otherwise start making it.
That is a narrower target than a topical steroid, which acts through glucocorticoid receptors present in many skin cell types and is covered in what steroid creams actually do. The difference that matters clinically is structural. Tacrolimus ointment "did not reduce skin thickness and did not cause skin atrophy in animals" and "does not affect collagen synthesis in humans" (Protopic SmPC), and the British Association of Dermatologists puts it plainly for both drugs: "They do not cause skin thinning or stretch marks, or some of other side-effects associated with the prolonged use of topical steroids" (BAD, Topical calcineurin inhibitors). Both sit in the same regulatory category, "agents for dermatitis, excluding corticosteroids".
The two drugs, their strengths and their licensed ages
Tacrolimus comes as an ointment in two strengths, and the strengths are licensed for different ages. Protopic 0.1% "is indicated in adults and adolescents (16 years of age and above)". Protopic 0.03% covers adults and adolescents from 16 on the same terms and, separately, children from the age of 2 who "failed to respond adequately to conventional therapies such as topical corticosteroids" (Protopic SmPC). Neither strength is for the very young: "Protopic ointment should not be used in children aged below 2 years until further data are available."
The severity band is moderate to severe in both cases, for patients "not adequately responsive to or are intolerant of conventional therapies such as topical corticosteroids". There is a second licensed use beyond treating a flare: maintenance treatment to prevent flares in people who have four or more exacerbations a year, applied once a day twice weekly with two to three treatment-free days between applications. The ointment "can be used for short-term and intermittent long-term treatment. Treatment should not be continuous on a long-term basis".
Pimecrolimus is a different proposition. Elidel 1% cream is licensed for "treatment of patients 3 months of age and older with mild or moderate atopic dermatitis where treatment with topical corticosteroids is either inadvisable or not possible" (Elidel SmPC). Milder disease, younger licensed age, and a condition attached to the steroid rather than to the response. A thin layer goes on twice daily, and it "may be used on all skin areas, including the head and face, neck and intertriginous areas, except on mucous membranes". The SmPC adds that treatment "should be initiated by physicians with experience in the diagnosis and treatment of atopic dermatitis".
Where NICE places them
NICE CG57 covers atopic eczema in children under 12, so its wording is written about children, but it is the clearest published statement of the position. It repeats the appraisal line: "Topical tacrolimus and pimecrolimus are not recommended in NICE technology appraisal guidance for treating mild atopic eczema, or as first-line treatments for atopic eczema of any severity" (CG57, 1.5.1.21).
The two drugs then get separate recommendations. Tacrolimus is an option "for the second-line treatment of moderate to severe atopic eczema in children aged 2 years and older that has not been controlled by topical corticosteroids, where there is a serious risk of important adverse effects from further topical corticosteroid use, particularly irreversible skin atrophy" (CG57, 1.5.1.22). Pimecrolimus is an option on narrower ground: "second-line treatment of moderate atopic eczema on the face and neck in children aged 2 years and older" under the same conditions (CG57, 1.5.1.23). Two thresholds have to be met, not one: the steroid has not controlled the eczema, and continuing it carries real risk.
Starting either one is a specialist decision. CG57 says to "start treatment with tacrolimus or pimecrolimus only with specialist dermatological advice, and only after careful discussion" of the risks and benefits of all the appropriate second-line options (1.5.1.24). If a GP has not offered one, that is usually the reason.
Why the face is where this question starts
The site that most often triggers the conversation is the face, because facial skin is where a steroid's time limit bites first and where eczema is managed under stricter rules. CG57 puts the step directly: "For facial atopic eczema in children that requires long-term or frequent use of mild topical corticosteroids, consider stepping up treatment to topical calcineurin inhibitors" (1.5.1.27). Repeated short courses on the same patch of cheek or eyelid, rather than one long course, is the pattern that fits that recommendation.
What using them is actually like
The characteristic effect is felt on application. In the tacrolimus clinical studies "approximately 50% of patients experienced some type of skin irritation adverse reaction at the site of application", with burning and itching very common, usually mild to moderate and tending to resolve within a week (Protopic SmPC). Elidel lists application site burning as very common, at one in ten or more, with irritation, itch and redness common, generally early in treatment and short-lived. Alcohol intolerance, meaning facial flushing or skin irritation after an alcoholic drink, is listed as common on tacrolimus.
Two cautions come with the class. Sun exposure should be minimised, and light from a solarium or UVB and PUVA therapy avoided during treatment (Protopic SmPC), with sunscreen, clothing and less time in the sun advised on pimecrolimus. And in children they are not to be used under bandages or dressings without specialist dermatological advice (CG57, 1.5.1.26).
On the question people ask most: the BAD leaflet states "there is no evidence they damage the immune system or increase the risk of cancer", while the Protopic SmPC records that in transplant patients prolonged systemic calcineurin inhibition has been linked with lymphomas and skin cancers, and that for the ointment "a link between Protopic ointment treatment and development of malignancies has not been confirmed, but definitive conclusions cannot be drawn". Both statements are on the record, and a prescriber weighs them against the atrophy risk of the alternative.
How to raise it with a GP
What is useful to bring is a history, not a request. How many steroid courses that patch of skin has had this year, how long each lasted, which potency, whether it settles and returns within days, and whether the site is face, neck or eyelid. Those are the facts the recommendations turn on, and they are the same facts that explain why a treatment plan has stalled. Since specialist advice is the entry point for these drugs, the realistic ask is often a referral rather than a prescription, and the thresholds for a dermatology referral are written down.
Nothing here is a reason to stop a treatment already prescribed. Coming off topical steroids raises its own questions, and the MHRA's position on withdrawal reactions is the place to read about that. A calcineurin inhibitor is a swap made with a clinician who has seen the skin, not a substitution made at home.
References
- NHS. Atopic eczema: treatment. https://www.nhs.uk/conditions/atopic-eczema/treatment/
- NICE. Tacrolimus and pimecrolimus for atopic eczema, technology appraisal TA82, 2004. https://www.nice.org.uk/guidance/ta82
- NICE. Atopic eczema in under 12s: diagnosis and management, CG57, 2007, updated 2025. https://www.ncbi.nlm.nih.gov/books/NBK571009/
- Electronic Medicines Compendium. Protopic 0.1% ointment, summary of product characteristics. https://www.medicines.org.uk/emc/product/1608/smpc
- Electronic Medicines Compendium. Protopic 0.03% ointment, summary of product characteristics. https://www.medicines.org.uk/emc/product/1612/smpc
- Electronic Medicines Compendium. Elidel 10 mg/g cream, summary of product characteristics. https://www.medicines.org.uk/emc/product/4966/smpc
- British Association of Dermatologists. Topical calcineurin inhibitors, patient information leaflet. https://www.bad.org.uk/pils/topical-calcineurin-inhibitors/