Phentermine and Tenuate for Weight Loss: 5 reasons they are still important in 2025!
Phentermine and Tenuate (diethylpropion) were approved by the FDA for weight loss in 1959. Until recently, they were the main medications we used to help patients lose weight and keep it off. Over the past 2 years, it’s tough to turn on the TV without seeing an ad for the latest greatest weight loss injection. Even Oprah is talking about them!
So, with the availability of the GLP-1 weight loss medications, is there still a place for phentermine and tenuate? The answer is absolutely “Yes!” Here are the top 5 reasons phentermine and tenuate are still vital tools for weight management:
1. Phentermine and Tenuate are inexpensive
Who would have ever imagined we would have treatments for weight loss that cost $1,000 to $1,500 monthly? Well, Zepbound and Wegovy, while very effective, can be very expensive! And, current evidence supports using the medications chronically or risking weight regain if they are stopped.
While some patients have insurance coverage and others can use coupon programs or direct cash purchase, let’s face it – the GLP-1 medications can cost a small fortune!
Conversely, because they are available generic, even without insurance coverage both phentermine and Tenuate are very cost effective generally costing less than $50 / month.
In the graph above, the blue bars show the relative cost of the medications compared to the total pounds of weight loss in orange.
In the graph above, The blue bar shows average pounds of weight loss. On the orange bar, I divided the retail cost by the average pounds of weight loss. You can see the monthly price per pound of weight loss is ~$43 / pound for Wegovy, ~$18 / pound for Zepbound, vs. ~$2 for phentermine and tenuate. Quite the difference!
2. Phentermine and Tenuate often have less side effects
Wegovy and Zepbound can cause a lot of side effects – nausea, vomiting, diarrhea, constipation, heartburn, burping, headaches and fatigue. They can also (rarely – less than 1% of the time) cause acute pancreatitis and gallbladder attacks. These side effects do usually get less over time, but for some patients, they can come back – especially if eating out at restaurants, traveling, etc.
Conversely, phentermine and tenuate rarely cause GI side effects. If they do, usually constipation, or less commonly insomnia and jitteriness. Also, phentermine and tenuate don’t typically make you tired – in fact, they usually have the opposite effect. Both phentermine and tenuate have a very mild stimulant effect, which many people like – sort of like a long-acting cup of coffee. Further, on phentermine and tenuate, people tend to have better focus and get a lot done!
3. For many people, Phentermine and Tenuate can provide a meaningful amount of weight loss
Not everybody needs to lose 50 pounds. The average weight loss on Zepbound is 50 pounds, while Wegovy is 35 pounds. The weight loss on phentermine or Tenuate usually averages closer to 10% of the total body weight, or 25 pounds, if comparing to the Wegovy and Zepbound weight loss trials.
If 25 pounds of weight loss is enough for you to experience dramatic health benefits, do the things you want to do, and still have money left in your bank to travel, maybe phentermine or Tenuate is a reasaonable choice for your weight management journey!
4. Phentermine and Tenuate are easy to store and travel with
It doesn’t get much simpler than taking one pill a day. That’s usually how we prescribe phentermine and Tenuate.
Wegovy and Zepbound, on the other hand, are injected once a week. While this can be very convenient, it can pose some challenges while traveling. The medications generally need to be kept refrigerated, and if using a vial form, they can be breakable, and require insulin syringes.
All you need for phentermine or Tenuate is a glass of water!
5. Phentermine and Tenuate are easy to stop and get out of your system quickly
Sometimes you need to quickly get off of a medication – you have a medical complication, get pregnant, need an emergency surgery, etc. Wegovy and Zepbound each have a very long halflife of 5-7 days. They can still be detectable in the blood stream up to two months after the last dose! For example, the package insert of Wegovy warns that you should come off of it 2 months before trying to get pregnant. In addition, there is more risk for drug interactions – the Zepbound label recommends a second form of barrier contraception (in addition to birth control pills) for the first month at each new dose.
Conversely, phentermine and Tenuate have half-lifes of less than 15 hours, so are mostly out of your body within 3 days and have very few drug interactions.
And a Bonus Reason: Long history of safety
Because they were approved so long ago, phentermine and Tenuate have a safety history dating back over 60 years. With millions of people being treated for decades, it is highly unlikely there will be new safety concerns regarding either of these medications.
Conversely, we are learning more and more about Wegovy and Zepbound. Approved in 2021 and 2023, respectively, the enormous increase in prescriptions is giving us an opportunity to learn both about many benefits of the new treatments, but also about some risks. For example, the FDA just required both medications to include a warning in the safety information about risks of aspiration during general anesthesia or deep sedation.
Phentermine and Tenuate for Weight Loss in 2025
In summary, yes, phentermine and Tenuate remain important tools in our toolbox to help combat obesity. This isn’t to say that Wegovy and Zepbound aren’t great tools too – especially for patients with insurance coverage, and for people with a lot of weight to lose!
Be sure to discuss ALL of the treatment options with your provider so you can make the best individualized decision. After all, what do you have to lose, except perhaps some extra unwanted body fat!
