Are there any alternative treatments for psoriasis?

Hard to say. To my knowledge, there are no controlled clinical trials that demonstrate the effectiveness of alternative therapies for psoriasis. All of the evidence is anecdotal at best. Most of the things mentioned are probably safe to try.
Psoriasis. Psoriasis is a puzzle. Treatments that work wonders for one patient of psoriasis have no effect or benefit for another. Alternative treatments would include distress with yoga, omega-3 fatty acids, aloe vera, apple cider vinegar or dead sea salts can soothe psoriasis flare-ups when added to bathwater, capsaicin, emu oil, oats, and tea tree oil have been reported to help.