Acne occurs due to the blockage of oil produced by the sebaceous gland (sebum) passing through the pore, resulting in a clogged pore. It also results in eruptions known as pimples.
Although everyone is different, acne is usually caused by the build up of oil and dead skin in a pore. This build up of oil and dead skin is caused because of:
Hormonal Changes - These are particularly active in your teens. The main cause of acne is hormonal changes. Level of sex hormone rises when girls and boys reach the puberty age. This causes enlarging of the oil glands and increase in production of sebum, increasing the likeliness of pores to block. Hormonal changes occur in girls when menstrual cycle begins due to which they are more prone to acne problems. Pregnancy or even intake of birth control pills may also cause hormonal changes and may be the reason for the breakout of acne.
Plugged skin. Lots of skin cells can close the oil glands or pores, creating blackheads or whiteheads.
Bacteria. Bacteria can easily infect oil glands and pores and grow very quickly.
Family background. If you have acne, your kids are more likely to have it too.
Genetic Reasons. This factor also causes acne. If your parents were victims of acne at some point of their life then you are likely to suffer from it.

Stress and Other Factors That May Cause Acne. Stress may worsen your acne condition. In some people, emotional tensions may also cause acne. Humidity or pollution are environmental factors that cause acne. Drugs like lithium and cosmetics may also result in acne.

Dermatologists recommend scrubbing the face and neck with water and soap to get rid of toxins produced in the body that may cause acne. You reduce the chances of occurrence of acne or infection in pores by cleaning your face regularly. You may even develop permanent scars in infected area, if you do not take proper care and treatment.

?Prevention is better than cure.? So it is better that you avoid oily food that is hard to digest in order to prevent acne. Acne medications usually do not treat them completely. Therefore, in order to get rid of acne from its roots you should know what causes acne and take proper treatment for the same. Incase the problem persists for long, you should consult your dermatologist.