context: If you have psoriasis on your scalp, certain shampoos that are made for your scalp and not your hair can help with flaking, redness, and itching. In some cases, that may be all you need to get a handle on it. These shampoos have some of the same ingredients as the medicines and lotions your doctor might recommend for psoriasis on other parts of your body. You can get ones that treat mild to moderate psoriasis off the shelf at your local pharmacy. The two main ingredients in those are coal tar and salicylic acid. If you need something stronger, your doctor can prescribe it for you. Whether prescription or over-the-counter, these shampoos should only be used for short periods of time. And you'll need to be gentle with them. Your psoriasis can get worse if you scrub too hard. It's also important to follow your doctor's instructions Coal tar has been used to treat psoriasis for more than 100 years. You can find it in shampoos as well as creams, oils, and lotions. Shampoos with coal tar help with scaling, hardening, and thickening of the skin on your scalp by slowing down the growth of skin cells. They also can ease itching and make your scalp look better overall. To use this kind of shampoo, massage it into your scalp, leave it on for 5 to 10 minutes, and then rinse. Be aware, though, that shampoo with coal tar might make your scalp more sensitive to the sun. Tar can stay on your skin for 24 hours or longer, and your chances of sun damage go up during that time. Protect your head with a hat or stay in the shade if you're outside. If you have blond or other light-colored hair, shampoo with coal tar could make it darker. Treatments with coal tar also can stain clothes or skin. Some people don't like the way coal tar shampoos smell. You may want to use a regular shampoo and conditioner afterward to make your hair smell good and keep it shiny. Salicylic acid works well for a lot of skin problems because it helps you shed dead skin. With psoriasis, it helps lift, soften, and get rid of scales on your scalp. To use one of these shampoos, wet your hair and work the shampoo into a lather. Rinse and repeat. Use it at least twice a week or follow your doctor's advice. Try not to get it in your mouth, eyes, or nose, and don't use it if you have a rash or a cut. Shampoos with salicylic acid can make your scalp dry, and that can lead to more flaking. They also can irritate your skin, make you nauseous, or cause other problems if you use it too long and over too big of an area of your head. Talk to your doctor before trying one of these. Some salicylic acid shampoos have sulphur, which can stop fungus. If you also have a yeast infection on your scalp, this kind of shampoo may be right for you. You may need to use it once or twice a week after the infection has gone away to keep your scalp healthy. You'll need a prescription from your doctor for these. They're usually used for only a few weeks to help with swelling and redness. After that, your doctor may suggest you switch to a coal tar shampoo. Don't wet your hair before using this shampoo -- you put it on your scalp when your hair is dry and leave it for 15 minutes. Then wet your hair, lather in the shampoo, and rinse it out. Be sure to keep it off your face and away from your ears -- your skin is thinner in those areas. It's also important to wash your hands well afterward.