Lesions like acne? Or rash?
It is possible to be allergic to any product, including Minoxidil but this is pretty uncommon with the foam formulation. Minoxidil comes as a solution or a foam. The solution has a preservative ingredient in it (propylene glycol) which can commonly cause scalp reactions such as itching, flaking, irritation. The foam version of minoxidil does not contain this ingredient and patients tolerate it quite well. If you are using minoxidil solution, I would try switching to the foam version. if you are still experiencing these problems while using minoxidil foam, then you may just want to discontinue using minoxidil.
It is possible albeit not that common. Patients get intense redness and sometimes blisters. It can be painful! See a dermatologist to differentiate irritation from allergy and other causes of scalp redness and flaking, including seborrheic dermatitis and psoriasis.
