I have used 30% (thirty) H2O2 on my face and scalp regularly for three months now and have gotten very good, if painful results. The yeast, malessazia, carries the protein catalase which catalyzes with hydrogen peroxide to decompose it in to water and oxygen. It also creates some heat which can be very painful but I like so many others here have tried so many remedies with limited succes and was desperate.
I have gotten rid of the seb. completely in my face and still working on the scalp. The H2O2 does not burn skin unaffected by the yeast although I have found that some areas infected by the yeast can be unaffected by it. I can not recommend this aggressive treatment for others because it is painful and can burn badly (like a bad sunburn) on spots where the yeast is dense. But I offer it as an example that H2O2 is good against seborrheic dermatitis caused by malessazia yeast.
First it attacks the yeast only, not surrounding skin and secondly, the byproducts are H2O, O2 and heat...sometimes very hot indeed! So maybe in smaller doses preventatively and apparently not in combination with vinegar either (see post above in the acv and h202 section)! Furthermore, I do not use anything else on my skin to moisturize it, no oils or creams. I wash with sea salt water and Resdan shampoo occasionally. I expect to move to a maintenance program involving diminished H2O2 combined with the same cleansing regime.