What antibiotic would be the best to treat sever acne in a female adult?

How severe?: Never use an antibiotic as sole treatment for acne. I trust you are also using topical benzoyl peroxide. Systemic tetracycline can be a good adjunct. A woman can use spironolactone and/or the oral contraceptive pill to get clear. If the acne is likely to produce scars, or doesn't clear well on the Rx's I've mentioned, isotretinoin may be a life-saver -- acne is a grave professional liability.

Depends: Antibiotics by themselves is not a very accurate way to treat acne. Acne should be treated in different battlefronts. Antibiotics is one of them. You should consider a skin care line that is specific to treat acne. Also look for other systemic conditions that will place you at risk for acne. Hope this helps.