Living with psoriasis doesn’t necessarily mean you have to overhaul your skin- or scalp-care routine. Psoriasis is caused by immune system dysfunction, not external irritants, so you can use many topical products safely as long as they don’t cause skin damage. However, anything with the potential to cause trauma to the skin—like a potent acid or strong surfactant—could spell trouble.
One reason topicals can lead to flare-ups is the Koebner phenomenon, which is when “local trauma stimulates the immune system to develop psoriasis in the traumatized skin,” says Shira Y. Wieder, MD, a board-certified dermatologist at Montefiore Einstein Advanced Care in New York City. When this happens new plaques appear in “healthy” areas of skin where there was previously no visible psoriasis.
The Koebner phenomenon does not affect everyone with psoriasis; frequently cited research estimates it occurs in about 25% to 30% of patients. “Not everyone with psoriasis has this response, but if you’ve ever watched a plaque appear at a cut, a scratch, or a sunburn, assume you’re someone who does,” says Omar Noor, MD, a New York City-based board-certified dermatologist.
Even if you don’t experience Koebnerization, applying a potentially irritating product to an area with visible psoriasis could worsen an existing flare-up. “If you have sensitivity [to an ingredient], then, yes, that’s going to trigger irritation to your skin, which will result in a flare in your psoriasis,” says Divya Shokeen, MD, a board-certified dermatologist and the founder of OSVI Dermatology and Surgical Institute in California. That’s why it’s important to do a small patch test anytime you try a new product to see if it triggers a reaction.
Overall, there’s a pretty big risk difference for patients whose psoriasis is controlled with medication or other treatments and those whose psoriasis isn’t. “If you haven’t found a treatment that controls your psoriasis yet, your skin is already primed to react, and a product that causes even mild trauma can seed a new plaque at that spot,” Dr. Noor says. “If your psoriasis is controlled, especially on a systemic treatment like a biologic, that risk drops substantially, but not to zero.” The key is knowing what’s likely to irritate your skin during a flare and what may spark an issue day-to-day even when your skin is clear.
Dr. Noor says patients with psoriasis in general should prioritize hydration in their skin-care routine. This can help soften plaques, improving both their appearance and any discomfort they cause. If you want to experiment with other types of ingredients—or are eager for a new tattoo or hair color—here are some guidelines on what you should approach with caution.
