Appetite Suppressants for Weight Loss

Reviewed by: HU Medical Review Board | Last reviewed: June 2023

When people think of weight loss drugs, they often think of appetite suppressants. These drugs are often called “diet pills.” Their official name is anorectics. They are prescription drugs that are used for people who are living with obesity or have weight-related health problems.1

How do appetite suppressants work?

Appetite suppressants work by curbing hunger cues in the brain and increasing the feeling of fullness (satiety). This leads to reduced appetite and reduced food intake, which may then lead to weight loss.1

Appetite suppressants are meant to be used along with a nutritious diet and exercise. Studies have shown that when combined with these lifestyle changes, people may see a 3 to 9 percent loss in weight within the first 12 months of starting the medicine.1

Examples of appetite suppressants

Several prescription appetite suppressants are used for weight loss and obesity treatment.

Phentermine (Adipex-P®, Lomaira™)

Phentermine is a stimulant that affects the central nervous system. It works by suppressing appetite through the release of norepinephrine. This reduces hunger signals to the brain.1-3

Phentermine comes in the form of a capsule that is taken by mouth. It is typically prescribed for short-term use and should be overseen by a doctor.1-3

Phentermine is approved by the US Food and Drug Administration (FDA) for adults. It has not been approved for use in children.1-3

For more information, read the full prescribing information of phentermine.

Phentermine-topiramate (Qsymia®)

Qsymia is a combination of 2 drugs: phentermine, an appetite suppressant, and topiramate, an anticonvulsant drug that also affects appetite. The way it works is not fully understood, but experts believe it increases satiety and reduces food cravings.4,5

Qsymia is approved by the FDA to treat people with obesity. It is an extended release capsule that is taken by mouth. It is approved for adults who have a BMI of:1,4,5

  • 30 or greater
  • 27 or greater, with at least 1 weight-related condition such as high blood pressure or type 2 diabetes

Qsymia also is available for children ages 12 years and older who have a BMI at the 95th percentile or greater for their age and gender.5

For more information, read the full prescribing information of Qsymia.


Phendimetrazine is another appetite suppressant that is FDA-approved for the treatment of obesity in adults who have a BMI of:1,6

  • 30 or greater
  • 27 or greater, with at least 1 weight-related condition such as high blood pressure or type 2 diabetes

Phendimetrazine comes in the form of an extended release capsule, taken by mouth. It is related to amphetamines and is considered a Schedule 3 controlled substance. Because of its risk of dependency, it is meant for short-term use under the close supervision of a doctor.6

For more information, read the full prescribing information of phendimetrazine.

What are the possible side effects?

Side effects can vary depending on the specific drug you are taking. The most common side effects of appetite suppressants are:1-6

  • Constipation
  • Dizziness
  • Dry mouth
  • Headaches
  • Irritability
  • Increased blood pressure or heart rate
  • Nausea and vomiting
  • Sleep problems or insomnia

These are not all the possible side effects of appetite suppressants. Talk to your doctor about what to expect when taking appetite suppressants. You also should call your doctor if you have any changes that concern you when taking an appetite suppressant.

Other things to know

Appetite suppressants are not recommended for people with cardiovascular disease. This includes those with high blood pressure (hypertension) or coronary heart disease.2-4

Do not take these drugs if you are pregnant, planning to become pregnant, or breastfeeding. Also, do not take these drugs if you have:1,3-5

  • Glaucoma
  • Heart disease
  • Overactive thyroid (hyperthyroidism)
  • Kidney problems
  • Liver disease

In rare cases, appetite suppressants may cause liver damage. If you notice signs of liver disease, such as yellow skin and eyes (jaundice), call your doctor.1

Appetite suppressants can interact with other medicines, including antidepressants and anti-anxiety drugs. Before beginning treatment for obesity, tell your doctor about all your health conditions and any other drugs, vitamins, or supplements you take. This includes over-the-counter drugs.5

Talk with your doctor

Appetite suppressants should be taken for weight loss only under the close guidance of a healthcare professional. Talk with your doctor about whether appetite suppressants are right for you.

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