Medicines are chemicals or compounds used to cure, halt, or prevent disease; ease symptoms; or help in the diagnosis of illnesses. Advances in medicines have enabled doctors to cure many diseases and save lives.
These days, medicines come from a variety of sources. Many were developed from substances found in nature, and even today many are extracted from plants.
Some medicines are made in labs by mixing together a number of chemicals. Others, like penicillin, are byproducts of organisms such as fungus. And a few are even biologically engineered by inserting genes into bacteria that make them produce the desired substance.
When we think about taking medicines, we often think of pills. But medicines can be delivered in many ways, such as:
liquids that are swallowed
drops that are put into ears or eyes
creams, gels, or ointments that are rubbed onto the skin
inhalers (like nasal sprays or asthma inhalers)
patches that are stuck to skin (called transdermal patches)
tablets that are placed under the tongue (called sublingual medicines; the medicine is absorbed into blood vessels and enters the bloodstream)
injections (shots) or intravenous (inserted into a vein) medicines
No medicine can be sold unless it has first been approved by the U.S. Food and Drug Administration (FDA). The makers of the medicine do tests on all new medicines and send the results to the FDA.
The FDA allows new medicines to be used only if they work and if they are safe enough. When a medicine's benefits outweigh its known risks, the FDA usually approves the sale of the drug. The FDA can withdraw a medicine from the market at any time if it later is found to cause harmful side effects.