If an itchy scalp has you scratching your head about a cause, it's time to do some investigating. While lice is a common concern for families with school-age children, there are many other reasons for itchiness, or pruritus, of the scalp. Seborrheic dermatitis, psoriasis, and inflammation due to physical injury are all conditions that can affect the scalp, causing embarrassing dandruff and annoying itchiness.
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The Scalp: An Ideal Environment
You may associate the scalp with a healthy, full head of hair. You might be surprised to learn what else can grow up on top of your head. As explained in the Journal of Investigative Dermatology, the layers of skin that make up your scalp contain hundreds of hair follicles and the sebaceous glands that secrete the oily sebum. While this is the ideal environment for growing your hair, the dense hair and moist scalp also make a great breeding ground for many parasitic organisms.
It is also important to note that your scalp has an ample supply of nerves. As noted in Experimental Dermatology (December, 2011), at least four types of nerves run to the hair follicles. Therefore, your scalp can be very sensitive if its tissues are damaged or irritated by parasites or physical injury. You may experience this sensitivity as an itching sensation.
Like most people, you probably groom your hair every day. Many of your grooming activities can injure and weaken the tissues of the scalp resulting in inflammation. According to the Journal of Investigative Dermatology, harsh brushing and combing and excess heating with blow dryers and curling irons are rough treatments that your scalp may endure daily. This causes dry, damaged scalp tissue, which is prone to itching and to parasitic invasion. The American Academy of Dermatology recommends using a conditioner after shampooing and letting your hair air dry instead of blow drying. These steps will help keep your scalp from becoming excessively dry and inflamed.
The American Academy of Dermatology (AAP) describes seborrheic dermatitis as a chronic skin condition. In adults, seborrheic dermatitis appears as oily, scaling patches of skin characterized by redness and mild inflammation. You may see an adult with a more intense condition develop oily crusts that are thick and yellowish.
There is no cure for this condition, so the treatment is to control the symptoms. Since it is believed this condition is caused by excessive growth of yeast on the skin’s surface, the goal of the treatment should be to decrease the yeast on the scalp and to loosen any patches of crusty, scaling skin. Your doctor may also prescribe a medication to treat infections secondary to this condition and to reduce the itching.
The AAP describes psoriasis as a condition that you can get when your immune system goes awry and signals your skin cells to start multiplying rapidly. The excess cells pile up and form lesions on the skin. The most common type of psoriasis, plaque psoriasis, causes scaling lesions that appear in patches and take on a silvery, red, or white appearance. Researchers have identified genetic factors predisposing certain people to this malfunction of the immune system.
Depending on the type and severity of the psoriasis, your dermatologist may prescribe different treatments. If you have a mild case of psoriasis, he may prescribe a topical ointment that you apply to your scalp. For more severe cases, your dermatologist may recommend phototherapy, in which ultraviolet light is applied to the skin, or may prescribe a medication to be given in an oral dose, by injection, or through an IV.