Is clarithromycin the best oral antibiotic for a single, deep &tender hormonal cystic acne lesion?the 5 day script i've taken hasn't healed it. thanks

Cyst: no antibiotic is the best and most of the time cystic lesion like you describe may need to be lanced and drained, try some warm compresses also, it may help for cyst to come close to the skin surface and drain on its own

Cystic Acne: Not likely. The antibiotic may temporarily reduce the acute inflammation secondary to infection but will not resolve the deep cystic lesion. It will likely resolve with steroid injection and possibly extraction if it becomes more superficial. You will also need better control of your hormonal outbreaks.