Can You Take Phentermine and Semaglutide Together?

Key Takeaways:

• Phentermine and semaglutide are two medications used for weight loss that work in different ways. Phentermine is meant for short-term use, and semaglutide is generally intended for longer use.

• You may be able to take phentermine and semaglutide together if your doctor thinks you may benefit from both, since the two medications don’t directly interact with each other. 

• Doctors generally only recommend taking multiple weight loss medications if one isn’t effective on its own.

• Phentermine and semaglutide are both FDA-approved for weight loss individually, but their safety and effectiveness together haven’t been evaluated.
  

Phentermine and semaglutide are among the most common weight loss medications. If you’re already taking one, you may be wondering whether you can take them together.

The short answer is yes. When one medication alone isn’t effective, doctors sometimes recommend the dual use of two weight loss medications. Using multiple medications may be highly effective at stimulating weight loss, but it also means there’s twice the chances of developing side effects.

The effectiveness of phentermine and semaglutide together hasn’t been well researched, so most of what we know is based on anecdotal evidence. 

Keep reading to learn about the potential benefits and potential risks of using semaglutide together with phentermine.

Phentermine is an appetite suppressant that falls into a group of medications called sympathomimetic amine anorectics, a group of stimulants. 

These drugs stimulate the release of chemicals in your central nervous system, such as norepinephrine and adrenaline that help reduce your appetite and increase fullness. 

Phentermine is sold under various brand names, such as:

• Adipex-P^®

• Obenix^®

• Lonamin^®

Phentermine was originally FDA-approved in the United States to help with weight loss in 1959. The medication was originally only approved for periods fewer than 12 weeks in combination with lifestyle changes, diet, and exercise.

Nowadays, there are still more than 2 million prescriptions filled for phentermine each year in the United States. A mix of phentermine and the anticonvulsant topiramate is sold under the brand name Qsymia^® and has been approved for long-term weight loss in people with obesity or overweight and related complications.

Phentermine is classified as a Schedule IV controlled substance due to its stimulant properties. Drugs in this category are considered to have a low risk of overuse or dependence.

Learn more about phentermine.

Semaglutide is a glucagon-like peptide-1 (GLP-1) receptor agonist originally developed to treat type 2 diabetes. It’s now widely used for weight loss under brand names like Ozempic^®, Rybelsus^®, and Wegovy^®.

Wegovy is FDA-approved to aid with weight loss for people with overweight or obesity when combined with exercise and dietary changes. 

Rybelsus and Ozempic are frequently prescribed off-label for this purpose but are currently only FDA-approved to treat type 2 diabetes complications.

Semaglutide and other GLP-1 agonists mimic a hormone produced by your gut called GLP-1, which:

• Slows stomach emptying

• Helps regulate blood sugar levels

• Reduces appetite and cravings

Semaglutide can be administered as a once-weekly injectable medication or as an oral medication. 

Learn more about semaglutide. 

Yes, but with some caveats. 

Phentermine and semaglutide work in different ways, and neither medication is strictly prohibited (contraindicated) when you’re taking the other.

Some forms of semaglutide, such as Wegovy, have a specific warning that they shouldn’t be mixed with other GLP-1 agonists. Other medications in the GLP-1 agonist category include:

• Dulaglutide (Trulicity^®)

• Exenatide extended-release (Bydureon^®)

• Exenatide (Byetta^®)

• Liraglutide (Victoza^®)

• Lixisenatide (Adlyxin^®)

The Wegovy label also notes that the safety or effectiveness hasn’t been studied in combination with other weight loss medications.

The label for Rybelsus^® and Ozempic^® doesn’t include this warning since they’re only FDA-approved to help people with type 2 diabetes manage blood sugar, even though they’re frequently prescribed off-label to aid with weight loss.

There’s also a warning on the label for products containing phentermine that it hasn’t been evaluated when combined with other medications.

So while you may be able to take semaglutide and phentermine together, it’s important to do so with caution and only when your doctor advises you that the potential benefits may outweigh the risks.

Generally, medical professionals recommend trying one medication before trying two.

There’s a lack of scientific research evaluating the results of taking semaglutide and phentermine together compared to taking either medication alone.

In a 2023 review of studies, researchers reviewed 168 studies examining the effectiveness of various weight loss drugs. The researchers found that semaglutide and phentermine (studied as the combination phentermine/topiramate) were associated with greater amounts of weight loss than other medications. However, the researchers didn’t evaluate the combination of these two medications.

Learn more about how phentermine and semaglutide compare. 

The potential risks and side effects of combining phentermine and semaglutide aren’t fully understood. The two medications aren’t known to directly interact, but taking two medications potentially exposes your body to twice as many side effects as taking one. 

Phentermine Side Effects

Common side effects of phentermine can include:

• Dry mouth

• Unpleasant taste in your mouth

• Increased heart rate

• Insomnia

• Anxiety

• Constipation

• Elevated blood pressure

More serious concerns include:

• High blood pressure (hypertension)

• Valvular heart disease

• Impaired ability to operate heavy machinery

• Development of tolerance

Semaglutide side effects

The most common side effects of semaglutide include:

• Nausea

• Abdominal pain

• Diarrhea

• Decreased appetite

• Vomiting

• Constipation

Rarer but potentially more severe complications include:

• Inflammation of your pancreas (pancreatitis)

• Diabetic retinopathy complication

• Low blood sugar (hypoglycemia)

• Acute kidney injury

• Hypersensitivity reactions

• Gallbladder injury

Learn more about semaglutide side effects. 

Taking phentermine and semaglutide isn’t suitable for people with conditions that make them ineligible for either medication.

The combination may be unsafe for those with:

• Unstable hypertension

• Unmanaged cardiovascular disease

• Glaucoma

• Heart disease

• History of pancreatitis

• Eating disorders

• Type 1 diabetes

• History of suicide attempts

• A family history of MTC or MEN 2 syndrome

• History of drug overuse

Phentermine should never be used with monoamine oxidase inhibitors.

It’s important to undergo a detailed medical history review before starting either medication. 

Medical professionals generally recommend changing lifestyle habits before trying medications for weight loss, unless you have complications that could cause major health problems, like severely high blood pressure. 

Some changes you can make to lower your body weight include:

• Eating a balanced diet, focusing on whole, unprocessed foods

• Increasing exercise

• Including incidental exercise in your daily routine (like taking the stairs instead of an elevator)

• Reducing stress

• Getting plenty of sleep

Find more weight loss tips here. 

Using semaglutide together with phentermine is potentially safe when done under medical supervision. There’s a lack of research looking at the safety or effectiveness of combining these two medications, but they aren’t known to directly interact with others.

It’s generally only recommended to try multiple medications for weight loss if one medication alone hasn’t proven to be effective. It’s important to tell your medical professional about any other medications you’re taking whenever you start a new medication.

Even if you decide to take medications to aid your weight loss, chronic weight management is most effective when you combine medications with healthy exercise and diet choices. 

If you’re wondering if you may make a candidate for semaglutide or other weight loss medications, you can talk to a licensed doctor through our telehealth service. 

Can you take phentermine and semaglutide together safely?

You can potentially take phentermine and semaglutide at the same time, but it’s important to only do so under proper medical supervision. There are no clinical trials examining the safety of taking both medications together. 

Why would my healthcare provider prescribe semaglutide with phentermine?

Your healthcare provider may consider prescribing multiple weight loss medications at the same time if you aren’t able to meet your weight loss goals with one medication alone, especially if you have weight-related health complications.

What are the most common side effects when combining semaglutide with phentermine?

The potential side effects of combination semaglutide and phentermine therapy haven't been fully evaluated. Common side effects of semaglutide include nausea, diarrhea, and vomiting. Common side effects of phentermine include dry mouth, unpleasant taste in your mouth, and an increased heart rate. 

Can semaglutide and phentermine speed up your weight loss journey?

Some people experience faster or more significant weight loss when they take multiple weight loss medications compared to taking one medication. It’s important to only take multiple medications if your doctor says it's okay, since doing so may increase the risk of side effects.