Ozempic vs. Phentermine for Weight Loss: Which Is Better?

If you’re suffering from obesity or experiencing the negative impacts of other weight-related conditions, you may be seeking a weight loss solution that will finally make the difference in your ongoing weight loss journey. For many patients, turning to a medical professional for help with chronic weight management is a positive experience that ultimately triggers substantial weight loss and healthy lifestyle modifications.

While bariatric surgery is one long-term medical intervention for weight loss, many patients prefer to opt for less invasive approaches, such as prescription drugs (or sometimes both surgery and drugs in combination). But which weight loss drug will be the right fit for you? Though your doctor will undoubtedly conduct a thorough examination that takes your own personal circumstances and medical history into account, walk you through the pros and cons of each potential medication, and ultimately help you decide which one makes the most sense for you, it’s always empowering to come to a medical appointment armed with research and knowledge.

In this post, we’re going to talk about the differences between two popular weight loss drugs: Ozempic and Phentermine. While none of the information provided here constitutes medical advice, it should provide you with a reasonable starting point for a more in-depth conversation with your doctor.

Let’s take a look:

What Is Ozempic?

Ozempic is a brand-name prescription medication manufactured by Novo Nordisk. It’s approved for the treatment of Type 2 Diabetes in adults as well as for the reduction of cardiovascular risks in patients with both Type 2 Diabetes and cardiovascular disease.

Semaglutide, the active ingredient in Ozempic, has been associated with weight loss in people with Type 2 Diabetes as well as in patients without Type 2 Diabetes. Though Ozempic is not approved for weight loss (prescriptions written for this purpose are considered off-label), another semaglutide-based drug known as Wegovy (also produced by Novo Nordisk) was recently FDA-approved for weight loss at a higher dose than Ozempic (2.4 mg).

How Does Ozempic Work?

Ozempic belongs to a class of drugs known as GLP-1 receptor agonists. GLP-1 (glucagon-like peptide 1) is an incretin hormone naturally produced in the gut during digestion. Semaglutide mimics this hormone, thus stimulating the natural release of insulin from the pancreas and triggering a variety of body systems to react as though digestion is underway. Semaglutide also slows down gastric emptying (the rate at which food moves from the stomach into the small intestine) and the digestive process as a whole.

Ozempic is an injectable medication that comes in pre-filled, single-patient-use pens. It’s taken via once-weekly injection and comes in multiple dosages ranging from 0.25 mg up to 2 mg (0.25 mg, 0.5 mg, 1 mg, and 2 mg). Patients typically begin at a 0.25 mg dose and build up to a higher therapeutic dose over a series of weeks or months to increase tolerance and decrease side effects.

How Does Ozempic Cause Weight Loss?

Ozempic causes weight loss by essentially tricking the body into believing that digestion is underway and communicating feelings of satiety or fullness. Because it also slows down digestion, food remains in the digestive tract for longer, which reduces hunger pangs and cravings.

What Is Phentermine?

Phentermine is a stimulant medication that’s one of the oldest weight loss drugs around. It received its FDA approval in 1959 and has been in use ever since. Phentermine is not approved for long-term usage, though it’s sometimes prescribed off-label for chronic weight management. It’s typically prescribed for an average of twelve weeks and should not be prescribed to anyone below the age of 17. If, during the course of taking Phentermine, your body stops reacting to the drug, your doctor will either adjust your dosage accordingly or recommend discontinuing usage.

How Does Phentermine Work?

Phentermine works by curbing your appetite. It stimulates your central nervous system, sending a chemical message to your brain that you’re satiated or full—even if you’re really not. In some cases, Phentermine can also increase your energy levels and even lift your mood, though not every person’s body chemistry will react this way to the drug.

Taken orally, Phentermine is available as capsules, tablets, or orally disintegrating tablets. It comes in strengths of 15 mg, 30 mg, or 37.5 mg and is taken once or twice daily, usually after breakfast and perhaps again later in the afternoon.

How Does Phentermine Cause Weight Loss?

Phentermine is an appetite suppressant, so it causes weight loss by reducing feelings of hunger. It does this by stimulating your central nervous system, thereby triggering the brain chemicals responsible for communicating feelings of fullness.

Ozempic vs. Phentermine: Which One’s More Effective for Weight Loss?

Both Ozempic (semaglutide) and Phentermine can be effective for weight loss. Let’s take a look at what the research says:

Ozempic

Clinical trials have found that Ozempic (semaglutide) can have significant implications for weight loss. A 48-week trial where patients took a 2.4 mg weekly dose of semaglutide resulted in a loss of 33.7 lbs, on average. A 68-week trial at the same dosage found that patients lost an average of about 10% of their starting body weight. A third recent study found that 23.5% of patients achieved weight loss of more than 20% after six months on a 2.4 mg dosage of semaglutide.

Ozempic is most effective in combination with lifestyle changes that include a healthy diet and exercise.

Phentermine

A quantitative analysis of four decades of clinical research for Phentermine found that patients taking Phentermine lose an average of about 14 lbs. in between 2 and 24 weeks. Though Phentermine is not approved for long-term use, anecdotal reports have indicated that off-label prescriptions for chronic weight management have resulted in more substantial weight loss.

Side Effects

Ozempic

The most common side effects of Ozempic involve gastrointestinal issues such as constipation, diarrhea, nausea, vomiting, and abdominal pain. These frequently resolve over time as your body adjusts to the medication.

More serious side effects include kidney, gallbladder, or pancreas issues, vision problems, and severe allergic reactions. You should not take Ozempic if you’re pregnant or have a personal or family history of Medullary Thyroid cancer or Multiple Endocrine Neoplasia Syndrome Type 2.

Phentermine

Common Phentermine side effects include dry mouth, jitters, increased heart rate, anxiety, irritability, constipation, and insomnia. Often, many of these symptoms resolve over time.

More severe side effects can include cardiovascular issues such as high blood pressure, heart attack, stroke, and very rarely, primary pulmonary hypertension or valve regurgitation.

Can You Take Ozempic and Phentermine Together?

Though there have been reports of people taking Ozempic and Phentermine simultaneously, the drug combination has not been adequately studied and isn’t recommended. Speak directly with your healthcare provider about questions related to the safety and efficacy of taking more than one weight loss drug at the same time.

Conclusion

Ozempic and Phentermine are both prescription drugs that can positively impact weight loss outcomes. While Phentermine is a stimulant that’s been on the market for decades, Ozempic is a GLP-1 receptor agonist that’s currently approved for the treatment of Type 2 Diabetes (though its counterpart, Wegovy, has been approved for weight loss).