Phentermine (Adipex-P, Lomaira) is an amphetamine-like prescription medication used to suppress appetite. It can help weight loss by decreasing your hunger or making you feel full longer. Phentermine is also available in combination with topiramate for weight loss (Qsymia).

Like other prescription weight-loss drugs, phentermine is intended to be used as part of an overall weight-loss plan. It is indicated for people who are obese, and who have failed to lose enough weight with diet and exercise alone — not for people who want to lose just a few pounds.

Phentermine is a Schedule IV drug, a classification given to drugs that have a potential for abuse, although the actual potential appears to be low.

Common side effects of phentermine include:

• Increased heart rate
• Tingling or prickling feeling in hands or feet
• Dry mouth
• Sleeplessness
• Nervousness
• Constipation

Although phentermine is one of the most commonly prescribed weight-loss medications, it isn't a good option if you have heart disease, high blood pressure, an overactive thyroid gland or glaucoma. It also isn't for women who are pregnant, may become pregnant or are breast-feeding.