Dandruff, Seborrheic Dermatitis, and Shampoos
Patient Information Sheet
Dandruff is the shedding of dead skin from the scalp in little white chunks of scale. Dandruff is not a disease. Everyone has it to some extent. Here's why.
The skin of the scalp is the thickest and fastest growing skin of the body. It has a very rich blood supply. If you have ever seen how much a small cut on the scalp bleeds, you know what I mean.
Because the skin of the scalp is growing so fast, the dead skin layer builds up rapidly. The hairs hold it in place. So, instead of being gracefully shed a few cells at a time as occurs on the back of your hand, it comes off in thick, noticeable chunks. These chunks are the flakes of dandruff. But, that is not a disease. It is not an infection or an inflammation.
Thus, dandruff is normal. It is as normal as the growth of your fingernails. You cannot prevent it. The problem is that we are so civilized, that we reject it. That is, it is socially undesirable. To decrease dandruff, we use shampoos that wash away the scale.
Seborrheic dermatitis seems like severe dandruff, but it includes inflammation. It causes a red, itchy, scaly, sometimes-greasy rash on the scalp. It can also occur on the ears, the eyebrows, the sides of the nose, the fold going from the sides of the nostrils to the lips (nasolabial folds), the middle of the chest, the middle of the back, under the arms, and in the groin areas. Seborrheic dermatitis is fairly common. Some doctors feel it is not a disease because it is so common, and they tend not to treat it. I disagree with that opinion. If you do a biopsy of seborrheic dermatitis, it shows inflammation. Specifically, various types of white blood cells migrate out of the blood vessels into the skin. Well, to me, that is not a normal state of affairs. That's inflammation. It is a disease process and deserves to be treated. So, I treat seborrheic dermatitis.
The word "dermatitis" is sort of a vague term that is used for any rash, an area that gets red, scaly, and itchy. It does not tell you exactly what is wrong. There are thousands of types and causes of dermatitis. It is the doctor's job to figure out as precisely as possible what kind of dermatitis is present. Seborrheic dermatitis is a specific kind of dermatitis.
We don't know what causes seborrheic dermatitis. It is not an infection. There is some evidence that overgrowth of a common skin fungus, Malassezia, can aggravate seborrheic dermatitis. Usually, it is not a sign of internal disease. Some neurologic diseases, such as Parkinson's disease, aggravate seborrheic dermatitis. Interestingly, in such cases, the increase in seborrheic dermatitis may match the side of the body affected by the neurologic disease.
Each hair follicle has several oil glands associated with it. Seborrheic dermatitis seems to involve a chemical irritation related to the oil produced by these oil glands. Since the oil glands are called sebaceous glands, we call the rash seborrheic dermatitis. I performed a large literature search on seborrheic dermatitis in 1991 and found that this is the present notion of this problem. It has not changed in 20 years.
Treatment of Seborrheic Dermatitis
The treatment of seborrheic dermatitis involves two parts. Firstly, we use cortisone lotions to clear up the rash. Once that is resolved, we rely on special shampoos to prevent recurrences. This is not a cure. The rash will tend to come back from time to time. We are just controlling it.
The topical cortisone lotions such as Synalar solution, Lidex solution, Valisone lotion, and so on lotion should be applied to the itchy, scaly, red areas of the scalp two or three times a day until the rash clears up. This same medicine can be used for the ears. Don't stuff it down into your eardrums. For the ear canal, apply the lotion to the tip of your little finger and gently rub it into the skin. See my separate information sheet.
The same medicines can be used in most other areas except the face. They are too strong for the face and especially around the eyes. For the face, I use a milder cortisone cream such as Westcort cream or Locoid Lipocream. Wet the rash areas and rub in the medicine twice a day until it clears up.
Most of the time, this treatment will clear up the rash and itch in a few days. It could take longer, but usually not.
Other rarely used treatments include Diflucan (fluconazole) an antifungal pill; pimecrolimus (Elidel), an anti-inflammatory cream; and Azelex, an acne cream;
To prevent recurrences, I prefer the use of shampoos. There are four kinds:
- Shampoos with tar
- Shampoos without tar
- Shampoos with selenium sulfide such as Selsun and Exsel (not Selsun Blue)
- Ketoconazole (Nizoral) shampoo
Which shampoo should you use? I used to try to give people with seborrheic dermatitis a wide variety of samples to try. The idea is to please you. You just have to try them out and see which ones you like the best. But, it is hard to get free samples anymore. I'll give you what I've got. Make a list and try out the free starter samples one at a time. Save the samples. You might find that what you like in the summer is different from what you like in the winter.
The tar shampoos are brown or black in color. They work the best. I suggest alternating between the tar and the non-tar shampoos. If you want, you can use the tar shampoo daily. Or you may want to use it once or twice a week and use the non-tar shampoo the rest of the week.
The selenium shampoos require a prescription. They are good shampoos, but I don't think they are better than the non-selenium shampoos. It's a matter of what works and what you like.
Most of the time, you can control seborrheic dermatitis with shampoos. When it breaks out, resume the topical cortisone medicine until the rash clears up. Then stop the topical cortisone and go back to the shampoos.
Nizoral shampoo is of special interest. It contains an antifungal drug. Some doctors claim that the microorganism Malassezia aggravates seborrheic dermatitis. Their claim is that Nizoral shampoo inhibits the growth of Pityrosporum ovale and thus improves seborrheic dermatitis. When I performed a large literature search on this topic, I found just as many articles saying Nizoral Shampoo helps as articles saying that Nizoral does not help. It may be worth trying Nizoral Shampoo for a couple of months to see if it helps you. It is not a cure. The question is whether it helps at all.
By the way, the claims being made in favor of Nizoral shampoo are the same that were being made for the selenium shampoos way back in the 1950's.
You can buy all these shampoos without a prescription except for the selenium shampoos and Nizoral shampoo. A less strong version of selenium (Selsun) shampoo is Selsun Blue which you can buy without a prescription.
Medication ingredients aside, shampoos are essentially detergents. They act by decreasing the Van der Waal's forces that hold water molecules adjacent to each other at the surface of water. They are surfactants. As the surfactant in the shampoo dissolves the oil off the hairs, the oil uses up the surfactant capability of the shampoo and the suds disappear. So you must rinse your hair and apply another dab of shampoo during that same shampooing. The conditioners in the shampoo with work better if you rinse off the used up surfactant-oil product.
You can try the same thing with bubble baths. When you take a bubble bath, the oil comes off your body and the bubbles disappear. So you need to add more bubble bath. Adding more bubble bath to the bath water does not work as well as the sudsing before getting into the tub because there is body oil in the water after you have soaked in the tub a few minutes. The only way to get around this is to empty and rinse the tub and to start all over. Enjoy the first few minutes of you bubble bath.
Conditioners are different from shampoos. Shampoos are detergents that wash the oil from the hair. As more oil is removed from the surface of the hairs and mixes with the shampoo, the sudsing decreases. This is why the shampoo seems to work better if you rinse out the first application and apply a second application.
Conditioners coat the hairs with an electrostatic charge. The electrostatically alike charges, usually + +, cause the hairs to repel each other. This gives the illusion of more body to the hair, to fluff up the hair. This is especially helpful cosmetically for people with thin hair or people losing hair. Some conditioners also help to reduce the tendency of long hairs to get tied up into tangles. They make hair easier to brush and comb. Many shampoos today contain conditioners. If the shampoo already contains a conditioner, it may not be useful to use a separate conditioner.
Another approach is to coat the hairs with materials that make the hairs look thicker. Beware of labels that claim to nurture the hair with vitamins or DNA. Hair is dead. It is not going to be nurtured.
Rev. Jan. 28, 2010 copyright Dr. Tkach
The information provided in these patient information sheets is offered for general informational and educational purposes only; it is not offered as and does not constitute medical advice. In no way are any of the materials presented meant to be a substitute for professional medical care or attention by a qualified practitioner, nor should they be construed as such.