An itchy scalp, also known as dermatitis is a very common medical condition and, when at serious intensities, can be quite annoying as the affected areas of the skin will tend to itch excessively. There are a number of possible reasons that the condition could develop and each would need to be dealt with accordingly. Contact dermatitis is probably the most common of them all and could be caused by switching to a new shampoo, soap or hair dye. In most cases, some alcohol content will be present in the substance that you expose your scalp to. If you notice that the product that has triggered the reaction does not do so in most other people, the chances are that you suffer from some kind of allergic reaction to an ingredient of the product.
Dandruff is another very common reason for an itchy scalp and is most prevalent in adolescents and gets worse in early adulthood. Moisturizing your head daily will go a long way into effectively treating this type of condition though. If you notice a red rash on your daughters scalp, she is more likely to be suffering from psoriasis. The condition is also characterized by the thickening of the scalp as well as the presence of a silvery scaling. While the condition is said to be hereditary – where it is passed down from one generation to the next within the same blood line, no medical proof has been established to substantiate this as yet. Since you mention that the itchiness is most prominent after your daughters scalp is exposed to water, you may want to check if the water in the pool is over chlorinated. If this is the case, a simple application of skin lotion should to the trick. However, if the condition occurs when the scalp is exposed to the same type of water that does not cause a reaction in most other people, she is most likely suffering from aquagenic pruritus which is a reaction of the skin to normally processed water.
Since the first few conditions are very common and can be treated with a variety of easily available products, we will look at a few treatment options for aquagenic pruritus. The condition will cause a change in your lifestyle and working around the problem is really the only way to reduce the extent to which it can disrupt your daughter's daily schedule. Before bathing or swimming, apply some amount of an oil based emollient lotion on the affected parts of the skin as this will control the amount of water content that comes in direct contact with the skin, thereby significantly reducing the extent to which the condition will develop.
answered by M W