Losing weight is not easy. When diet and exercise don't seem to work, you may be tempted to try diet pills.

Diet pills are called weight loss supplements when purchased over the counter and called weight loss medications when prescribed by a physician. But, how safe are they?

Drug stores and health food stores are filled with a wide variety of pills, creams and other substances that promise to burn your fat, reduce your weight and stop hunger pangs. Americans spend nearly $2 billion on them every year. So, they must be good...right?

Well, there is no medical evidence that these over-the-counter diet aids do any good. In fact, they could be hazardous to your health.

It can be extremely risky to take any medicines without a doctor's supervision. Diet pills are designed to react in the body a certain way and may have potentially serious side effects. These side effects could be anything from rash, insomnia or digestive upsets. They may also interact with prescribed medications that you are on and can cause even more serious problems.

If you really feel you need diet pills to help you lose weight, they should be prescribed by a doctor. They are not to be used to lose 5, 10, or even 20 pounds, but are for people who need to lose a large amount of weight.

There are three main types of diet medications. The first type uses a medication that works like amphetamines to decrease your appetite. Although they are safer than the amphetamines that used to be on the market, they are usually prescribed for just a few weeks because of the possibility of becoming addicted to them.

Another type of prescription drug (Sibutramine or Meridia) is an appetite suppressant that targets the appetite-control center in the brain. It can raise blood pressure, so regular visits to your doctor are essential.

The third type blocks digestion of the fat a person consumes (Orlistat or Xenical). The undigested fat passes through the body. You may need to take a vitamin supplement while on this medication because it blocks the absorption of vitamins A, D, E and K.

Diet pills alone will not help you lose weight and keep it off. It comes back to remaining on a healthy diet and ongoing physical activity. Prescription weight loss medication will give you a start, but it's up to you to continue eating nutritious meals and continuing your exercise plan.