Im on keflex for tooth infection for last 5 days. its still hurting. does that mean its not working?

Not Necessarily: Dental infections can take a while to subside. What procedure was performed? The dentist who is treating you and prescribed the antibiotics should be consulted to have that area reevaluated.

Possibly: The infection may take more time to clear or a different antibiotic may be required. Note that most dental infections require actual physical treatment, such as root canal or extraction. Antibiotics control the spread of infection, but cannot "cure" an infected tooth. Please see your Dentist.

Temporary solution: Keflex is an antibiotic, not a pain killer. It can temporarily shrink down an infection, and therefore may reduce your pain for a short time. Unless you have the source of the infection treated with a root canal or by extracting the tooth, it will come back as soon as you are off the antibiotic. You must have dentist finish treating your tooth.