Melasma can worsen with just about anything other than sunscreen and lightening agents. Lytera is a great topical medication that we investigated at our practice and have published on. Our studies showed that Lytera worked to lighten pigmentation as equally as hydroquinone without the irritation that would alter your rosacea. In addition it has niacinamide, which has been found to suppress redness - so it could help you two-fold. If that wasn't enough, I would be evaluated for an IPL which also targets both redness and pigment. Of course the treatment can always worsen melasma temporarily , as anything can, but I have done it on multiple people willing to take the chance, with great success. Good luck!