Dandruff and fungus
Dandruff is a common problem that affects both men and women. The medical term for this condition is also Seborrheic dermatitis. It is a very common condition of the skin that leads to white flakes or scales on the scalp and few other areas such as inner ear or eyebrows. It is the most commonly seen problem of the scalp and the treatment is mostly only symptomatic that involves regular use of shampoos or medicinal oils that can bring temporary relief.
Basically, the white flakes we see as dandruff are skin cells. Our skin naturally regenerates every few weeks and as the new skin cells travel through the bottom layers to reach the topmost layer of the skin, the dead skills are shed on a regular basis. This is usually microscopic in nature and not as easily noticed. However, in the presence of dandruff, the shedding of dead cells increases as well. What we see sometimes as dead cells with skin oils that form big white flakes that are easily noticeable.
Most commonly, dandruff is believed to be caused by a fungus that commonly lives on skin and acts on oils from the human skin. This fungus, called malassezia multiplies and can cause dandruff and other symptoms such as scaling or itching. However, since this fungus occurs on the skin almost universally, the exact cause of why this fungus sometimes multiplies and causes dandruff is still poorly understood. Some of the possibly conditions that are believed to aid in triggering this fungal growth response include: chemical treatments that sometimes harm the hair, poor hygiene, overuse or under use of shampoos to name a few. The incidence is dandruff is also higher in winters relative to summers, which may be due to the higher level of exposure to sunlight in summers. However this is not very clear and overexposure to sunlight can cause other problems of the skin and scalp.
If you suffer from dandruff continuously for a period of time, and have already tried the common methods or the anti dandruff oils and shampoos that are available, it is advisable to consult your doctor/dermatologist for a conformed diagnosis. They can then help you chose the right treatment which may involve ketoconazole etc which is an antifungal agent.
Some cosmetic usage can cause allergic reactions of the skin like dermatitis, contact dermatitis etc. Eczema also commonly called atopic dermatitis also develops on the scalp.
Dandruff shampoos or oils
There are many over the counter shampoos for dandruff that you may try that can contain one or different combinations of the following: sulfur, salicyclic acid, coal-tar preparation, pyrithione zinc, selenium sulfide, ketoconazole (eg. 1% or 2% Nizoral) to name a few. You can try one or a combination of more to see if it helps with your dandruff and if none of these work as much to keep your scalp clear, your dermatoligist should be able to supplement these with some medication in the form of oils, shampoo, hair care products or even oral medication.