Does cephalexin work on an abscessed tooth?

Usually: Usually Cephalexin will work for an abscessed tooth. It does however take 24-48 hours for the antibiotic before you will start to feel better.

Possibly.: Cephalexin, also called by its brand name keflex, is a cephalosporin antibiotic. It has a good chance of being effective on the bacteria in the abcess but will not kill those bacteria inside the nerve canal in the tooth and so the abcess will return when you stop taking the cephalexin. Only a root canal treatment or an extraction can really solve the problem.