Prophylaxis (Greek "προφυλάσσω" to guard or prevent beforehand) is any medical or public health procedure whose purpose is to prevent, rather than treat or cure a disease. Roughly, prophylactic measures are divided between primary prophylaxis (to prevent the development of a disease) and secondary prophylaxis (whereby the disease has already developed and the patient is protected against worsening of this process).
Antibiotics are sometimes used prophylactically: For example, during the 2001 anthrax attacks scare in the United States, patients who were believed to be exposed were given ciprofloxacin. Similarly, the use of antibiotic ointments on burns and other wounds is prophylactic.
Antimalarials such as chloroquine are used both in treatment and as prophylaxis by visitors to countries where malaria is endemic to prevent the development of the parasitic plasmodium which cause malaria.
Professional cleaning of the teeth is dental prophylaxis.
Daily and moderate physical exercise in various forms can be called prophylactic because it can maintain or improve one's health. Cycling for transport appears to very significantly improve health by reducing risk of heart diseases, various cancers, muscular- and skeletal diseases and overall mortality.
Prophylaxis may be administered as vaccine. Prophylactic vaccines include: PEP, nPEP, PREP, or nPREP. PEP stands for post-exposure prophylaxis used in an occupational setting. nPEP is non-occupational post-exposure prophylaxis. nPEP may be used in a recreational setting e.g. during intercourse if the condom breaks and one partner is HIV-positive, nPEP will help to decrease the probability of spread of infection of HIV. PREP is often used in occupational settings e.g. in hospital staff to prevent the spread of HIV or Hepatitis C from patient to staff. nPREP is a measure taken before exposure but in a non-occupational setting (non-occupational Pre-exposure prophylaxis) e.g. injection drug users may seek nPREP vaccinations.