What do you take to ease the pain of a tooth abscess ?

Antibiotics: You need to see a dentist to have the abscess evaluated. Afterwards, the dentist will usually give you a prescription for antibiotics to control the infection. Once the infection is controlled, the pain will subside. The offending tooth will need to be treated to prevent the infection from returning, antibiotics are only a "temporary" fix and without definitive treatment, it will come back.

Pain due to tooth : Try Ibuprofen 600mg every 6hrs (if you are allowed to take it). If the pain does not subside, you may also supplement with 500mg tylenol (acetaminophen). Visit your dentist/endodontist asap, as a root canal is needed regardless.