For example, insulin is a hormone used to treat diabetes. The female sex hormones estrogen and progesterone are used in birth control pills. Estrogen may be given as a replacement therapy to relieve uncomfortable symptoms associated with menopause including sweating, hot flashes, and mood swings. Estrogen replacement therapy may also delay some long-term consequences of menopause including osteoporosis and atherosclerosis. Anti-infective drugs interfere selectively with the functioning of a microorganism while leaving the human host unharmed.
Antibacterial drugs act by interfering with some specific characteristics of bacteria.
Antibiotics often cure an infection completely. However, bacteria can spontaneously mutate, producing strains that are resistant to existing antibiotics. Antiviral drugs interfere with the life cycle of a virus by preventing its penetration into a host cell or by blocking the synthesis of new viruses. Vaccines are used as antiviral drugs against diseases such like mumps, measles, smallpox, poliomyelitis, and influenza. Vaccines are made from either live, weakened viruses or killed viruses, both of which are designed to stimulate the immune system to produce antibodies , proteins that attack foreign substances.