Eucrisa (crisaborole) burns because it’s being applied to skin that already has a damaged barrier. About 4% of patients in clinical trials reported application site pain, primarily described as burning or stinging, compared to just 1% using the inactive ointment base alone. The sensation is real, common enough to be the drug’s most frequently reported side effect, and there are clear reasons it happens.
Damaged Skin Exposes More Nerve Endings
The burning you feel isn’t an allergic reaction or a sign that the medication is harming your skin. It’s a consequence of applying a topical product to skin that’s already compromised by eczema. In atopic dermatitis, the outer layer of skin is disrupted by both inflammation and repeated scratching. That disruption exposes nerve endings that would normally be protected beneath an intact skin barrier.
Those exposed nerve endings aren’t just more accessible. In people with eczema, they’re also more reactive. Research published in The Open Dermatology Journal describes how nerve endings in eczema-affected skin become sensitized, increase in density, and can even grow longer or thicker than normal. This means the skin in your flare zones is essentially primed to detect and amplify any irritation, whether from a medication, a moisturizer, or even water. When Eucrisa contacts these hypersensitive nerves, the result is that familiar burning or stinging feeling.
The Ointment Base Plays a Role Too
It’s not only the active drug causing the sting. Each gram of Eucrisa contains crisaborole in a base of white petrolatum, propylene glycol, paraffin, and a few other inactive ingredients. Propylene glycol is a well-known culprit for stinging on broken or inflamed skin. It’s widely used in skincare products and is perfectly safe, but on skin with a compromised barrier, it can irritate exposed nerve fibers on contact.
This explains why the ointment base itself caused stinging in about 1% of trial participants. Even without the active ingredient, the vehicle can trigger discomfort on damaged skin.
Worse Flares Mean More Burning
The intensity of the burning generally tracks with how inflamed your skin is. When eczema is actively flaring, the barrier is at its weakest, nerve endings are most exposed, and sensitivity is highest. You’ll likely notice that Eucrisa stings more on red, raw, or recently scratched patches than on areas where the eczema is mild or nearly clear. As the medication starts working and inflammation settles down, the barrier begins to repair itself, and those nerve endings become less exposed.
The Burning Typically Fades With Use
The National Eczema Association notes that application site pain from Eucrisa typically resolves with ongoing use. This makes sense given the mechanism: as the drug reduces inflammation over the first week or two, the skin barrier gradually improves, nerve endings become less exposed, and there’s simply less raw tissue for the ointment to irritate. Many people find the burning is worst during the first few applications and diminishes noticeably within days.
In the Phase 3 trials submitted to the FDA, the pooled data showed that 4% of the roughly 1,000 patients using Eucrisa reported application site pain. In one trial the rate was 6%, in the other just 3%. So while burning is the most common side effect, the vast majority of users either don’t experience it or find it mild enough to continue treatment.
How to Reduce the Sting
The simplest and most effective trick comes directly from the American Academy of Dermatology: store your Eucrisa in the refrigerator. Applying it cold can prevent the stinging sensation entirely for many people. Cold temperatures help calm those sensitized nerve endings on contact, essentially numbing the initial irritation before it registers as pain.
A few other practical approaches can help. Applying a thin layer of plain moisturizer first and letting it absorb for a few minutes may create a slight buffer, though this can also dilute the medication. Avoiding application immediately after bathing, when skin is warm and pores are open, may reduce stinging for some people. And if burning is severe on a particular patch, that area may simply be too raw for topical treatment at that moment. Letting it calm down for a day or two before reapplying can make a noticeable difference.
If the burning is intense enough that you dread each application or it lasts longer than a few minutes, that’s worth raising with your dermatologist. There are other non-steroidal eczema treatments that work through different mechanisms and may be better tolerated on highly sensitive skin.