Phentermine is one of the oldest and most widely prescribed weight loss medications in the United States. Here's everything you need to know before deciding if it's right for you.
Phentermine is a Schedule IV controlled substance regulated by the DEA. This means it has potential for abuse and dependence, though lower than many other controlled medications. Because of this classification, phentermine requires close medical supervision, regular follow-up visits, and cannot be prescribed indefinitely. We take these requirements seriously to ensure your safety.
Phentermine is an FDA-approved prescription medication that suppresses appetite by affecting neurotransmitters in your brain. It's been used for weight loss since 1959, making it one of the most studied weight loss medications available.
The medication works by stimulating the release of norepinephrine in your brain, which reduces hunger signals and helps you feel satisfied with less food. It's classified as a sympathomimetic amine, similar in structure to amphetamines but with a much milder effect.
Studies show that patients taking phentermine along with diet and exercise typically lose 5-10% of their body weight over 12 weeks. For someone weighing 200 pounds, that's 10-20 pounds. While this may be less dramatic than newer GLP-1 medications, phentermine can be an excellent option for jumpstarting weight loss or for patients who prefer an oral medication.
Like all medications, phentermine can cause side effects. Most are mild and often improve as your body adjusts. However, some side effects require medical attention.
Usually mild and may improve over time:
Stop taking and contact your provider if you experience:
Because phentermine is a controlled substance, there is a potential for psychological dependence. Additionally, some people develop tolerance over time, meaning the medication becomes less effective. This is one reason it's typically prescribed for short-term use. If you notice the medication is no longer working as well, talk to your provider – do not increase your dose on your own.
Phentermine is NOT safe for everyone. You should not take this medication if you have any of the following:
Your provider will carefully evaluate you if you have:
Because phentermine is a controlled substance with cardiovascular effects, we require regular monitoring to ensure your safety and the medication's continued effectiveness.
Complete medical history, physical assessment, blood pressure check, and discussion of goals and expectations.
Brief visits to monitor weight, blood pressure, side effects, and assess continued appropriateness.
Every 3 months, a comprehensive follow-up to evaluate progress and determine if continuation is appropriate.
Through the end of 2025, we are able to prescribe phentermine via telehealth visits for established patients. However, due to evolving FDA regulations regarding controlled substances, in-person visits may be required for initial consultations starting in 2026. We'll keep you informed of any changes to these requirements.
Wondering how phentermine compares to newer medications like semaglutide or tirzepatide? Here's a quick comparison:
| Phentermine | GLP-1 / Tirzepatide | |
|---|---|---|
| How It Works | Stimulates brain to reduce hunger | Mimics gut hormones, slows digestion |
| Administration | Daily pill | Weekly injection |
| Typical Weight Loss | 5-10% body weight | 15-25% body weight |
| Duration | Short-term (12+ weeks) | Long-term use |
| Controlled Substance | Yes (Schedule IV) | No |
| Cost | $$ (Lower) | $$$ (Higher) |
Bottom line: Phentermine can be a good option for those who prefer an oral medication, want a lower-cost option, or need a short-term jumpstart. GLP-1 medications typically produce more significant weight loss and can be used long-term. Some patients use phentermine initially and transition to GLP-1 therapy, or use them in combination under medical supervision.
Note: Medication cost is not included. Your prescription will be sent to your preferred local pharmacy where you can fill it using your insurance or pay the generic cash price (typically $15-40/month).
Schedule a consultation to discuss your weight loss goals and determine if phentermine is a safe and appropriate option for your situation.
Questions? Text us at (910) 777-5888