DEAR DR. ROACH: Over 40 years ago, about six months after having our first child, I developed scalp psoriasis so badly that just a touch of my hair would send “flakes” flying in the air! It was itchy, it often bled, and it was highly embarrassing! I kept my hair short because the sun in the summer seemed to help ease the itching and help the patches go away.

After trying prescription shampoos, steroid topical lotions, and many over-the-counter treatments, in addition to at-home light treatments, I literally had my scalp psoriasis disappear overnight! A couple of months ago, I thought I would try an inexpensive, plant-based biotin and collagen shampoo that I found when my husband and I were grocery shopping. To my complete amazement, after using the shampoo that morning when I showered, the itching was gone, and my patches of psoriasis were nonexistent the next day! I didn’t know if it was a fluke, but the psoriasis hasn’t returned! My hairdresser said that there is no sign of dryness anywhere on my scalp, and she, too, was surprised that this shampoo worked! I also called my dermatologist to tell him my good news.

From what I read, biotin and collagen is OK to use topically. Have you ever found it to be detrimental to a person’s health when using a shampoo such as this one? I researched online and couldn’t find any info about whether it is good to use in this manner. — P.D.

ANSWER: Biotin, a type of vitamin B, is generally safe when taken by mouth and should certainly be safe when used topically. I did not find any evidence that biotin is effective for scalp psoriasis, where the usual treatment is topical steroids, but if it is working for you, you can absolutely keep using it.

I would caution you that psoriasis often has a clinical course where it seems to get better or worse for no good reason, so I can’t be 100% sure that your new shampoo has done the trick, although the timing certainly makes it seem so.

One symptom that I always warn my patients with psoriasis of: Take any joint pains seriously. There is a special type of arthritis that happens in a minority of people with psoriasis that can be rapidly destructive to the joints, so any joint pain, especially with redness and warmth, should be evaluated promptly.