As the name implies, preventive treatment is intended to make sure you don't catch or acquire or otherwise suffer from symptoms, a condition or disease. Preventive care is also called prophylactic care. Some examples are:
Vaccines: We are given vaccines to prevent certain diseases that are particularly debilitating, often for a lifetime, or may cause death. They may be injected, inhaled or swallowed. Once the vaccine is given, the immune system creates antibodies to fend off any exposure to the disease later in life. Examples include: childhood vaccines for diseases like measles or polio, vaccines against diseases like tetanus or the flu that are needed at any age, and vaccines used for specific diseases someone older might acquire, such as shingles.
Genetics: With the advent of personalized medicine, and the ability to review one's genetic code, there are some instances of preventive treatments being used to fend off diseases that may result from someone's biological heritage. An example of this type of preventive care would be for a woman found to have the BRCC genes that may signify certain forms of female cancers. A women found to have the BRCC gene might choose a preventive treatment like having a breast removed to prevent development of cancer in that breast.
Preventive care may also be part of our everyday routine. We brush our teeth to prevent tooth decay. We eat certain foods or avoid certain foods to keep cholesterol levels low, or take vitamins and supplements to build strong bones, or drink orange juice to stave off colds. We wear helmets when we ride bicycles to prevent head injuries. We exercise to keep our hearts strong.
Prevention is important enough to keep us healthy that US healthcare reform, the Affordable Care Act, built in the capability for patients to receive dozens of preventive screen tests at no cost.
If prevention doesn't work, then we may need one of the other forms of treatment.