An itchy scalp is irritating and unsightly. But it’s also frustrating if you don’t what’s causing it. explains what might be at the root of the problem, and how to handle this skin condition.

What’s Behind the Itch

Dandruff. These annoying flakes are the most common cause of an itchy scalp. Dandruff is caused by an overgrowth of yeast that lives on your scalp and other hairy areas. When there is a change in your body chemistry, the yeast fattens up by feeding on dead skin cells and oils. The result? Flaking and itching. To get rid of the itch and the dandruff, use an over-the-counter shampoo that contains selenium, zinc pyrithione or tea tree oil (all three help control yeast).

Salons. Surprise! Hair services such as repeated chemical hair treatments—think relaxers or permanent color—can suck moisture from your scalp. The result? Dryness and itching.

Styling. Yup, that blow-drying habit may be frying your scalp. Excessive heat can irritate and dry out the skin. To avoid this heat-caused itching, don’t blow-dry your hair, especially at the hottest setting and when hair is very wet.

Allergies. Your itch may be an allergic reaction. If you’ve recently changed styling products and noticed increased itching, you may be allergic to some product ingredient. Some hair stuff, especially sprays, contain ingredients that tighten the scalp as they dry. That sensation can lead to itchiness.

How to Stop the Itch

Very simple: moisturize. This means don’t wash your hair with hot water (which can strip away the scalp’s natural oils). Also, try products with moisturizing ingredients that work for you. Use conditioners formulated for your hair type, and deep condition periodically.

When to Worry About Scalp Itch

If you notice thick, scaly patches that hurt, crack or bleed, don’t just get worried—get to the doctor! You may have psoriasis, a chronic autoimmune disease. Or if your hair is falling out or breaking, or if you notice pus on your scalp, zoom to the doc so he or she can make sure you don’t have an infection.

When you scratch your head, do you notice any bumps? If you do, it’s time for a skin check. Click here to read more.