Appetite Suppressants

What are appetite suppressants?

Appetite suppressants are a type of weight-loss medication (sometimes called diet pills) for people who have obesity (a body mass index, or BMI, over 30). They affect how your body and brain experience appetite and hunger. Appetite suppressants can make you feel less hungry or make you feel full faster after eating less food. As a result, you may take in fewer calories and lose weight.

It’s important to know that appetite suppressants don’t work on their own. Studies show that they’re most beneficial for weight loss when you combine them with a reduced-calorie eating plan and regular physical activity.

Types of appetite suppressants

There are prescription and over-the-counter (OTC) appetite suppressants. Prescription appetite suppressants can be for long-term or short-term use.

Check with your healthcare provider before using OTC diet pills. Some OTC appetite suppressants may interact with medications or cause health problems.

Prescription appetite suppressants for long-term use

The Food and Drug Administration (FDA) has approved these prescription appetite suppressants for long-term use:

• Liraglutide (Saxenda®). This is an under-the-skin (subcutaneous) injection medication.
• Semaglutide (Wegovy®). This is an under-the-skin injection medication.
• Naltrexone-bupropion (Contrave®). This is a pill.
• Phentermine-topiramate (Qsymia®). This is a pill.

Prescription appetite suppressants for short-term use

Other FDA-approved prescription appetite suppressants are for short-term use only — typically up to 12 weeks (three months), including:

• Benzphetamine (Didrex®, Regimex®).
• Diethylpropion (Tenuate®, Tenuate Dospan®).
• Phendimetrazine (Prelu-2®).
• Phentermine (Dipex-P®, Atti-Plex P®, Pro-Fast® and others).

These short-term appetite suppressants are controlled substances. This means they have addiction potential and can be dangerous if you use them outside of their intended, prescribed use. If you have substance use disorder (SUD) or a family history of SUD, be sure to tell your healthcare provider before starting these medications.

Laws regarding how long you can take these types of appetite suppressants may vary from state to state.

How do appetite suppressants work?

Hunger, appetite and energy homeostasis (balance) are very complex bodily processes. They involve the interaction of several chemicals in your:

• Brain and nervous system.
• Pancreas.
• Adipose tissue (body fat).
• Stomach and the rest of your intestinal tract.

These chemicals include:

• Hormones: These are chemicals that coordinate different functions in your body. They come from endocrine system tissues and travel through your blood to target tissues. Some examples of hormones that play a role in appetite include ghrelin, leptin, insulin and cortisol.
• Neurotransmitters: These carry signals from one neuron (nerve cell) to the next target cell. Neurotransmitters like GABA and serotonin play a role in appetite.
• Peptides: These are chains of amino acids. They’re like small proteins. Glucagon-like peptide 1 (GLP-1) is one example of a peptide that’s involved in appetite.

Some of these chemicals increase appetite and hunger and others decrease them.

Prescription appetite suppressants work by blocking or increasing specific hormones, neurotransmitters and/or peptides. Each one works differently and targets different chemicals. But they generally work in two ways — making you feel less hungry or feel full faster when you eat.

Who can use appetite suppressants?

Healthcare providers only recommend appetite suppressants for people who have obesity — mainly when modified eating plans and increased exercise alone haven’t helped with weight loss. Obesity typically means you have a body mass index (BMI) of 30 or higher.

Providers may also recommend appetite suppressants if you have a BMI greater than 27 and have a condition or symptoms that may be related to obesity, like:

• Type 2 diabetes.
• High blood pressure.
• High cholesterol.
• Joint pain.

What are the advantages of appetite suppressants?

Studies show that prescription appetite suppressants, on average, help people achieve weight loss of 5% or more of their starting body weight. Again, these medications work best when you combine them with regular physical activity and a reduced-calorie eating plan.

An analysis of 143 studies revealed that phentermine-topiramate and GLP-1 receptor agonists (like liraglutide and semaglutide) are among the most effective medications for reducing weight in people with obesity. The typical body weight reduction with these medications is 6% to 11%.

What are the side effects of appetite suppressants?

Each type of appetite suppressant works differently, so they all have different side effects. Be sure to discuss side effects with your healthcare provider before starting a medication.

Common side effects of long-term prescription appetite suppressants include:

• Constipation.
• Diarrhea.
• Abdominal pain.
• Nausea.
• Indigestion.
• Headache.

Side effects of short-term prescription appetite suppressants that are controlled substances include:

• Rapid or irregular heartbeat (tachycardia or arrhythmia).
• Dizziness.
• Mood changes, like depression or anxiety.
• Cognitive (mental) changes like agitation, delirium or psychosis.
• Nausea and vomiting.
• Diarrhea or constipation.
• Abdominal pain.
• Insomnia.
• Headache.
• Dry mouth.

Are appetite suppressants safe?

Long-term prescription appetite suppressants are generally safe if you take them as prescribed. Short-term prescription appetite suppressants require more caution when you use them due to possible severe side effects and addiction potential.

Some appetite suppressants can interact with medications, including antidepressants and anti-anxiety drugs (anxiolytics). Appetite suppressants can also worsen certain health conditions — like high blood pressure, mood disorders and glaucoma, for example.

Again, each appetite suppressant works differently, so they have different risks. Talk to your healthcare provider about all the benefits and risks of each medication if you’re thinking of starting an appetite suppressant.

Safety of over-the-counter (OTC) appetite suppressants

Some OTC appetite suppressants or weight-loss supplements contain ephedra, ephedrine or caffeine (stimulants). And some have been linked to reports of heart attack, seizure, stroke and death. It’s important to talk to your healthcare provider first if you’re thinking of taking OTC appetite suppressants or supplements.

When should I see my healthcare provider if I’m taking an appetite suppressant?

If you’re taking an appetite suppressant, you should see your healthcare provider regularly to see if it’s working for you. You should also see your provider if you develop unpleasant or dangerous side effects (like irregular heartbeat and delirium).

A note from Cleveland Clinic

Obesity is a complex condition that requires a complex treatment plan. Prescription appetite suppressants may help. It’s important to have an in-depth conversation with your healthcare provider before starting an appetite suppressant to make sure they’re right — and safe — for you. Don’t hesitate to ask your provider questions. They’re available to help.