The dandruff shampoo could help with rosacea? Apparently for some people, yes.
Selsun Blue is a dandruff shampoo that contains Selenium Sulphide. It can also be used for the treatment of the skin conditions Seborrhea and Tinea Versicolor. Because of this some people suspect that those who claim Selsun Blue helped with their rosacea may have simply not had rosacea in the first place but another skin condition.
However, because there are theories that rosacea is caused by mites or fungii it might be possible that Selsun Blue (being an anti-fungal shampoo) could help eliminate these problems.
Note: It seems only the extra strength or medicated brand of Selsun Blue contain Selenium Sulphide. This is what I imagine people have used to treat rosacea because of it's use for other types of skin conditions. In at least one instance I recall reading that someone used the original brand successfully. There's a lot to consider... for example...
Amendement (Original may have Selenium Sulphide):
The base brand consists of six types including Medicated with menthol, 2-in-1, Normal to Oily, Moisturizing, Itchy Dry Scalp, and Deep Cleansing with micro beads. The first four types contain the active ingredient selenium sulfide which has been shown to have anti-fungal properties.
The Naturals brand of Selsun Blue contains salicylic acid which is an ingredient that many have discussed helping with Rosacea.
Some people say that simply rubbing the suds of Selsun Blue gently onto their face during a shower has helped improved their Rosacea. Although Selsun Blue is a slightly more expensive shampoo it could be worth a try. You might even have a bottle somewhere!