Question: What can cause a skin and scalp rash that won't go away? It consists of little white bumps that itch and break open when scratched. It spreads slowly, but persistently, no matter what I do. My doctor has prescribed a $425 prescription shampoo that stops the itching for about 24 hours but does nothing to get rid of the rash.

Dr. Hibberd's Answer:

There are many types of scalp rashes, and without knowing the age of the patient and other circumstances — as well as seeing a picture — I can offer you only a limited guide.

Scalp irritation may come from simple dandruff or infection (often fungal), cradle cap (infant children only), dermatitis from chemicals and other irritation/allergy, or even from chronic skin disorders, such as psoriasis. It sounds like you were given a custom preparation, and without more details, I cannot imagine why it was so expensive.

When doubt exists, it is not unusual to scrape lesions for fungal analysis and culture, and if other disorders are suspected, a small tissue sample can be sent for pathological analysis to aid and guide future treatment.

I recommend you consult with a dermatologist if your present treatment is not improving matters, or not clearing as expected, or if it worsens. Discuss your working diagnosis with your doctor, and be sure to understand how long it is expected you will need medication and how long before you start to visibly heal.