Wegovy versus phentermine

Wegovy vs Phentermine: A Comparison

When comparing Wegovy and Phentermine, two FDA-approved weight-loss medications, it’s crucial to understand their key differences. Wegovy, a newer injectable drug launched in 2021, aims to reduce appetite for long-term weight management. Phentermine, an oral medication available since 1959, works primarily by boosting energy and suppressing hunger for short-term use.

Wegovy versus phentermine

Too busy for the full read? Here’s what you need to know:

  • Both Wegovy and Phentermine are FDA-approved weight loss medications.
  • Wegovy, a newcomer in 2021, employs a novel injectable delivery method and works by reducing appetite through GLP-1 mechanisms, which makes it suitable for long-term use.
  • As a stalwart since 1959, Phentermine is an oral medication that stimulates energy levels and suppresses hunger, approved predominantly for short-term use.
  • Each medication boasts proven effectiveness, with both demonstrating statistically significant weight loss outcomes in clinical trials.
  • It’s crucial to note the distinctiveness of each medication: they come with their own set of side effects, cost implications, and contraindications that must be carefully considered.
  • As per FDA recommendations, the simultaneous use of Wegovy and Phentermine is not advised.

With new drugs such as Wegovy being made available to the US market, the choice of weight loss medications is becoming more extensive.

As part of our series on popular weight loss drugs, we will compare the latest medication, Wegovy, with the most widely prescribed drug, phentermine, so that you can decide if one of these anti-obesity medications might assist you with losing weight.

What Is Wegovy?

Only approved by the FDA in 2021, Wegovy is the latest weight loss drug launched to support chronic weight management.

Unlike many oral weight-loss drugs, Wegovy is injected once a week using a pre-filled injector pen. The pen contains semaglutide, a drug that mimics a hormone called glucagon-like peptide-1 (GLP-1). Semaglutide, sold as well under the brand name Ozempic, reduces the appetite, making it easier to lose weight. (1)

Across several clinical trials, Wegovy led to statistically significant weight loss. Non-diabetic participants who took part in a 68-week trial showed an average weight loss of 17-18%. This weight loss was sustained throughout the trial without weight regains occurring.

In a study of patients with type 2 diabetes, individuals who received Wegovy lost around 6.2% of their baseline body weight. (2) (1)

Unlike many other weight loss medications, Wegovy can be taken long-term, which may lead to more successful weight loss outcomes. Wegovy has also been prescribed as a successful treatment strategy for weight regain occurring after bariatric surgery. (3)

What Is Phentermine?

Phentermine was first approved by the FDA in 1959 for treating obesity.

Available as capsules or tablets, this weight loss medication contains phentermine hydrochloride, a stimulant with similarities to amphetamine. Phentermine rouses the central nervous system and causes the release of neurotransmitters, including epinephrine.

Due to its potential for side effects and the risk of dependency, phentermine is typically prescribed for short-term use, often for a period of 12 weeks or less, along with diet modifications and exercise.

This aids weight loss as the heart rate increases, energy levels are boosted, and the appetite is reduced. Phentermine will work best if taken alongside a low-calorie diet. (4)

As phentermine is an older drug, it has been studied in many clinical trials. Of participants taking the maximum dose of phentermine (37.5mg daily) for 3 months, around 50% can expect to lose at least 10% of their baseline body weight.

This average weight loss is considered clinically significant and beneficial to overall health.

Wegovy vs. Phentermine: A Side-by-Side Comparison

Wegovy and phentermine have both been proven to aid weight loss, but the two drugs work in different ways to achieve this. In the following table, we will compare Wegovy vs. phentermine to make it easier to understand the differences and similarities between the two.

Can You Take Wegovy and Phentermine Together?

Wegovy and Phentermine Together

You must not take Wegovy and phentermine together. The FDA recommends that only one weight loss product be taken at one time, including prescription drugs, over-the-counter preparations, and herbal remedies. (1)

Phentermine or Wegovy – Which One Is Better for Me?

If you are weighing up the pros and cons of Wegovy vs. phentermine, it is encouraging that both anti-obesity drugs have led to significant weight loss in clinical trials.

With an average weight loss of 17-18% for non-diabetic patients, Wegovy is an excellent choice for chronic weight management. The slow escalation schedule may help some people to avoid Wegovy’s digestive side effects.

However, this injectable has also been linked to thyroid tumors and is contraindicated in people with certain medical conditions. Wegovy is also a very expensive drug, especially if taken long-term.

As an older drug, phentermine has a long history of supporting weight loss and reducing the body mass index of obese and overweight people.

A generic pill is available, so it is an affordable option. Phentermine is available in a range of doses, and can therefore be titrated to avoid or minimize side effects. As an older drug that is commonly prescribed, some people may feel more comfortable trying phentermine as a first-line treatment for obesity.

It is important that you discuss pharmaceutical weight loss options with your doctor prior to treatment to ensure you take the right drug for your individual circumstances.


What are the main differences between Wegovy and Phentermine?

Wegovy, approved in 2021, is a weekly injectable medication that reduces appetite for long-term weight management. Phentermine, available since 1959, is an oral medication used short-term to increase energy and curb hunger.

Which weight loss drug is more effective, Wegovy or Phentermine?

Both drugs have proven effective in clinical trials, but the effectiveness can vary depending on personal health circumstances, specific weight loss objectives, and responses to medication. Always consult with a healthcare professional before choosing a weight loss medication.

Is semaglutide better than phentermine for weight loss?

While both semaglutide (the active ingredient in Wegovy) and phentermine aid in weight loss, they function differently. Semaglutide is designed for long-term usage and can lead to substantial sustained weight loss. On the other hand, phentermine is geared towards short-term use and can assist in rapid weight loss over a shorter duration.

Which drug is better for long-term weight management, Wegovy or Phentermine?

Wegovy is intended for long-term weight management, while Phentermine is typically prescribed for short-term use due to its potential side effects and risk of dependency.

Are Wegovy and Phentermine covered by insurance?

Wegovy may be covered by insurance, or you may be able to arrange coverage with Novo Nordisk directly. Some insurance plans may cover phentermine.


1. FDA.gov (Wegovy Approval).
2. NovoNordisk.com (Wegovy Trials).
3. Gazda CL et al. Pharmacotherapies for Post-Bariatric Weight Regain: Real World Comparative Outcomes. Obesity. 2021; 29 (5): 829-836.
4. FDA.gov (Phentermine Label).
5. Phentermine.com (Phentermine). 
6. RxList.com (Wegovy).
7. Phentermine.com (Phentermine Dosage).
8. NovoMedlink.com (Wegovy Dosage).
9. Phentermine.com (Side Effects).
10. Phentermine.com (Phentermine Warnings).
11. Wegovy.com (Wegovy Use).
12. Novocare.com (Wegovy Cost Navigator).
13. BlinkHealth.com (Buy Generic Phentermine).
14. PushHealth.com (Buy Wegovy).
15. Drugs.com (Generic Wegovy).