Topical calcineurin/calcineurin inhibitors, known generically as tacrolimus (Protopic) and pimecrolimus (Elidel) were approved by the FDA in 2001 for the treatment of mild to moderate atopic dermatitis (AD) in people aged two years and older who are not immune-compromised. They work by blocking the immune system’s inflammatory process, so they reduce inflammation of the affected skin as well the itch and rash associated with AD. Calcineurin inhibitors are used either intermittently for extended treatment or for a short term to manage acute flares. They are used when conventional therapies are not advisable, or the person has not responded to conventional treatment. The positive effects of treatment are usually noticeable within three days of starting treatment. One of the most common side effects of calcineurin inhibitors is an initial itchiness or burning, which usually disappears after the first few days of treatment. They can also cause headache, acne and increased sensitivity to hot and cold. Importantly, calcineurin inhibitors also increase your sensitivity to UV rays. If you’re using a calcineurin inhibitor it’s a good idea to avoid direct exposure to sunlight and UV exposure in general, including sun lamps and tanning beds. Although no causal link has been established, rare instances of cancer have been reported in people taking calcineurin inhibitors, so in 2005 the FDA added a boxed warning to both tacrolimus and pimecrolimus.