Seb derm is caused by malassezia yeast (aka fungus) and particularly by the hyphal phase. The key principle for treating malassezia is that it's lipid-dependent. It needs oil to survive. Washing more or fewer times is not likely to matter much, as it's impossible and unhealthy to remove all skin oil (sebum). Therefore, skin needs to be treated with a cream, which is why Lotrimin Ultra, or Nizoral 2% cream, is effective when combined with a climbazole-based shampoo.
Shampoo by itself is only going to work against very mild problems, like "dry dandruff," which is also caused by malassezia but is merely an annoyance. Selsun Blue is not effective for treating "oily dandruff," which is another name for seb derm and a fairly descriptive term. The hyphal yeasts form a biofilm that is difficult to penetrate. Head and Shoulders is another dry dandruff product that is not effective on seb derm.
Here’s a list of all the OTC climbazole shampoos:
1) Hegor’s 150 (1.5% Climbazole), which is made in France and is available in the US only on eBay and will be shipped from Bulgaria.
2) Alderma’s Bioderma Sensibio DS Gel containing unstated amounts of climbazole and piroctone olamine, which is available on Amazon and ships from Portugal.
3) Eucerin’s DermoCapillaire Antidandruff Gel Shampoo containing 0.5% piroctone olamine and 0.45% climbazole, which is sold only in the EU and is not available online, as far as I can tell.
Climbazole is much more effective when the pH is lowered by adding 0.3% to 0.9% citric acid. Low pH won't work so well as a hair shampoo because it makes hair slightly strawlike.
I tried Aloe Vera and found that it helped a little, but I recently started adding 2% to 5% Xylitol to everything I use. I’m inferring from candida research, that Xylitol prevents biofilm formation by making the keratin too slippery for the fungus to interact with the skin. We will always have malassezia because it’s commensal, or normally found, on all mammals’ skin.
The healing process in treating a fungal skin condition is like a time machine slowly going backwards. The medicine slowly dissolves the cells walls of the yeast and the contents of the yeast cells leak out and it dies. The redness results from your body’s immune system recognizing that there are fungal foreigners, to which the body’s first healing reaction will be redness and inflammation, which is normal. Do not be dismayed by additional patches of skin redness – your body is healing, although it may take weeks or months to become normal.
Aquaphor or Vaseline is somewhat useful too, because they have carbon chain lengths in the range of C25 to C30, and malassezia can metabolize oils only in the C10 to C24 range.