The answer depends on what type of gum infection you are talking about.

If you are talking about periodontal disease, then amoxicillin is given in some cases, but it is in combination with another drug called metronidazole. Amoxicillin (a form of penicillin) alone does not control periodontal infections because many periodontal bacteria are resistant to it.

Most forms of gingivitis and periodontitis can be successfully treated without antibiotics. Routine therapy is scaling and root planing: mechanical removal of plaque and calculus.

When antibiotics are used, the most common ones are tetracycline antibiotics, which include tetracycline hydrochloride, and doxycycline (a long-acting form of tetracycline). These antibiotics also reduce inflammation and help block collagenase, the enzyme produced by the anaerobic bacteria that destroys connective tissue and bone.

If you are instead talking about a local swelling in the gum due to a tooth infection, this is caused by different bacteria. This type of infection does respond to amoxicillin.