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Compare Wegovy vs. Phentermine

Head-to-head comparisons of medication uses, side effects, warnings, and more.

Key takeaways

Semaglutide (Wegovy) and phentermine (Adipex-P) are both prescription weight management medications, but they have important differences. Semaglutide is a glucagon-like peptide-1 (GLP-1) receptor agonist, while phentermine is a sympathomimetic stimulant. Semaglutide is FDA-approved for long-term weight management in adults and children aged 12 and older meeting certain body mass index (BMI) criteria. It also lowers the risk of heart problems in adults with heart disease. Phentermine, on the other hand, is approved for short-term weight management in adults aged 17 and older. Semaglutide is administered as a weekly subcutaneous injection, whereas phentermine is taken orally once daily. Phentermine is available in various forms, including tablets, capsules, and orally disintegrating tablets, and is available as a lower-cost generic. Common side effects of semaglutide include nausea and diarrhea, while phentermine may cause dry mouth, a fast heart rate, and trouble sleeping. Phentermine is a controlled substance due to its potential for misuse and dependence, but semaglutide is not.

Wegovy (semaglutide)
Phentermine (Adipex-P)
Wegovy (semaglutide)
Phentermine (Adipex-P)
Summary of Wegovy vs. Phentermine
Summary for GLP-1 agonist
Prescription only
Wegovy (semaglutide) is a glucagon-like peptide-1 (GLP-1) receptor agonist. It's an injection that's given under the skin. The medication is used along with a lower-calorie diet and regular exercise. Wegovy (semaglutide) is approved to help with weight loss in certain adults and children 12 years and over. It also helps lower the risk of heart attack, stroke, and death due to heart problems in adults with a larger body size and heart disease. And, it's also approved for certain adults with a liver problem called metabolic dysfunction-associated steatohepatitis (MASH). The dosing schedule is an injection once a week. Common side effects are nausea, diarrhea, and stomach pain.
Summary for Sympathomimetic
Prescription only
Phentermine (Adipex-P) is an appetite suppressant. It's a prescription weight loss pill for people ages 17 years and older. This medication works best when it's part of a treatment plan that involves healthy diet and regular exercise. Phentermine (Adipex-P) is taken by mouth once daily, typically in the morning. Some of the more common side effects of this medication include dry mouth, trouble sleeping, and headache.
Indications of Wegovy vs. Phentermine
Indications for

•
Weight loss and long-term weight management in:

•People ages 12 years and older who are considered obese

•Adults considered overweight with at least one weight-related condition (e.g., high blood pressure, Type 2 diabetes, high cholesterol)

•
Lowering the risk of heart attack, stroke, and death due to heart problems in adults with a larger body size and heart disease

•
Metabolic dysfunction-associated steatohepatitis (MASH) in adults with moderate-to-advanced liver scarring, but not cirrhosis

Indications for
Short-term treatment for weight management in adults with a body mass index (BMI) of:

•30 kg/m2 or greater; or

•27 kg/m2 or greater, and with at least one other weight-related condition (e.g., high blood pressure, high blood sugar, high cholesterol)
Pros and Cons of Wegovy vs. Phentermine
Pros and Const for GLP-1 agonist
Pros

•Can help you lose weight when it's used along with a nutritious diet and regular exercise

•Approved for helping with weight loss for children ages 12 years and older considered obese

•Injected once a week

Cons

•Must inject under the skin

•Can cause stomach pain, nausea, and diarrhea

•Can't take with other semaglutide products (Ozempic, Rybelsus) or with other GLP-1 agonists

Pros and Const for Sympathomimetic
Pros

•Can help you lose 5% to 10% of body weight

•Usually taken by mouth once per day

•Available as a lower-cost generic

•Comes as tablets, capsules, and orally disintegrating tablets

Cons

•Most insurance companies don't cover the cost of phentermine (Adipex-P).

•Has a risk of misuse and dependence since it's a stimulant medication that's similar to amphetamines

•Might not be a good choice for people with high blood pressure

•Should be avoided in children 16 years of age and younger, pregnant and breastfeeding women, and people with serious heart problems
Common Side Effects of Wegovy vs. Phentermine
Common Side Effects for

•Nausea (44%)

•Diarrhea (30%)

•Vomiting (24%)

•Constipation (24%)

•Stomach pain (20%)

•Headache (14%)

•Tiredness (11%)

Common Side Effects for

•Dry mouth

•Headache

•Tremor

•Constipation

•Diarrhea

•High blood pressure

•Fast heart rate

•Difficulty sleeping
Warnings of Wegovy vs. Phentermine
Common Side Effects for

•Possible risk for thyroid cancer

•Inflammation of the pancreas (pancreatitis)

•Gallbladder problems

•Low blood sugar

•Kidney damage

•Allergic reactions

•Eye problems in people with Type 2 diabetes (diabetic retinopathy)

•Faster heart rate

•Possible risk of self-harm

•Lung problems during general anesthesia or deep sedation

Common Side Effects for

•Not safe to combined with other weight loss medications

•Phentermine not working well

•Risk of misuse and dependence

•Trouble concentrating or problem with coordination

•Heart and lung problems

•Risk of high blood pressure

•Risk of low blood sugar in people with diabetes
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Key takeaways

Summary of Wegovy vs. Phentermine

Indications of Wegovy vs. Phentermine

Pros and Cons of Wegovy vs. Phentermine

Common Side Effects of Wegovy vs. Phentermine

Warnings of Wegovy vs. Phentermine

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