- "Antibiotics are chemical substances produced by certain microorganisms which are active against other microorganisms" - Brock et al, Biology of Microorganisms, 7th Edition
Antibiotics are a group of chemicals, discovered by Alexander Fleming in the early 1900s, which restrict the spread and growth of bacteria.
Note that antibiotics do not work against viruses, such as the common cold, influenza (flu) and measles. Their main therapeutic use in humans today is to combat infection, like that which causes toothache, skin infections, such as acne and abscesses, and internal infections, such as appendicitis and bacterial meningitis, among others.
Their main use as it relates to body modification is to treat wound infections, such as an infected pierced earlobe or nipple. If you feel your piercing is infected, consult your piercer, doctor or pharmacist.
If you are taking antibiotics for any reason, it's important to mention this fact to your piercer or tattoo artist, as some antibiotics may delay the healing process. Antibiotics should not be taken, nor should a course of antibiotics be stopped, without medical advice, as this may actually lead to an increased risk of infection.