Starting phentermine requires an in-person visit; refills can be virtual. Our practice prescribes phentermine, a Schedule IV controlled medicine, only after an in-person evaluation and exam at our Lehi, Utah clinic. After that first visit, refill visits can be completed by secure video. Prescriptions are sent electronically to your pharmacy; we do not write paper prescriptions.
Phentermine is an appetite suppressant that has been used for decades. It is inexpensive and may reduce appetite and support short-term weight loss for some patients. It is FDA-approved for short-term use, together with diet, exercise and behavior change, in adults with a BMI of 30 or higher, or 27 or higher with a weight-related condition such as high blood pressure, diabetes or high cholesterol. Here is how we use it, who it is for, and what side effects to watch for.
How we use phentermine
As a starter
Phentermine can help get weight loss moving while you build new eating and activity habits, or while you decide on a longer-term medicine such as a GLP-1.
Longer or on-and-off use
The FDA label approves short-term use (a few weeks). Using it longer or in cycles, such as 3 months on and 3 months off, is off-label; your physician may consider it case by case, after discussing the uncertain long-term benefits and risks, with regular check-ins.
As part of a program
Utah rules require it to be part of a full weight-loss program with nutrition, activity and regular monitoring, not a prescription on its own.
What starting phentermine involves
- In-person visit in Lehi with a complete history and physical exam, including blood pressure and heart rate.
- Review of past weight-loss efforts and your medical records.
- Informed consent. Utah requires a signed consent that includes the statement that the long-term effects of controlled substances for weight loss are not known.
- Electronic prescription sent to your pharmacy. No paper prescriptions.
- Regular follow-up to check your weight, blood pressure and side effects. Refill visits can be done by secure video; bring your home blood-pressure readings. Phentermine is stopped if it isn’t helping, if a reason not to take it develops, or if it isn’t taken as directed.
Visit fees are the same as our other weight-loss visits: $199 for the first visit and $149 for monthly follow-ups (see all prices). Generic phentermine is usually inexpensive; your pharmacy sets the price.
How to take it
- Once a day in the morning. Taking it late in the day can keep you awake.
- Avoid alcohol, and be careful driving until you know how it affects you.
- Don’t take a higher dose if it seems to stop working; tell us instead.
- If you have diabetes, tell us: because you’ll likely eat less, your diabetes medicines may need to be lowered to prevent low blood sugar.
- Don’t combine it with other weight-loss medicines or supplements unless your physician directs it.
- Tell us about all your medicines, including stimulants, decongestants and medicines for depression or ADHD, and any history of substance use.
Common side effects
- Dry mouth or an unpleasant taste
- Trouble sleeping, restlessness or feeling “wired”
- Faster heartbeat or a pounding heart
- Higher blood pressure
- Headache or dizziness
- Constipation or diarrhea (see our constipation guide)
- Changes in sex drive
Potentially serious side effects
These are rare. Stop phentermine and get care right away if you notice:
- Pulmonary hypertension: new or worsening shortness of breath, chest pain, fainting, or swelling of the legs or ankles. This is rare but can be fatal.
- Heart valve problems: rare cases have been reported, mostly when phentermine was combined with other weight-loss drugs.
- Very high blood pressure, chest pain or an irregular heartbeat.
- Misuse or dependence: phentermine is related to amphetamines; take only as prescribed and never share it.
- Serious allergic reaction: hives, swelling of the face or throat, or trouble breathing.
For a medical emergency, call 911.
Who should not take phentermine
People with heart disease (such as coronary artery disease, stroke, irregular heart rhythms or heart failure), uncontrolled high blood pressure, an overactive thyroid, glaucoma, a history of drug misuse, or agitated states; anyone who has taken an MAO inhibitor in the last 14 days; and anyone who is pregnant or breastfeeding.
Phentermine or a GLP-1?
In clinical trials, GLP-1 medicines produced more average weight loss over the long term than is reported with short-term phentermine, and they are used long term, but they cost more and have different risks; see the Wegovy pill and Zepbound without insurance. Phentermine costs less and may help some people early on, but is approved for short-term use. Had weight-loss surgery before? Read GLP-1s for weight regain after bariatric surgery. A home blood-pressure cuff is helpful on phentermine; see virtual monitoring.
Ready to talk it through?
Your first phentermine visit must be in person at our Lehi clinic (choose the in-person Lehi option when you book); refill visits after that can be by secure video. New weight-loss patient visit $199; monthly follow-up visit $149. Medication is billed separately by your pharmacy. See all prices.
Frequently asked questions
Can I get phentermine by video visit?
Not to start it. Our practice prescribes phentermine only after an in-person evaluation and exam at our Lehi clinic. After that, refill visits can be completed by secure video.
Can I get a paper prescription?
No. Our practice sends all controlled-substance prescriptions electronically to your pharmacy; we do not write paper prescriptions.
How long can I take phentermine?
The FDA label approves phentermine for short-term use as part of a weight-loss program. Using it longer or on and off, for example 3 months on and 3 months off, is off-label; some physicians consider it case by case when it is safe and working, with regular check-ins. Your physician decides whether that fits you.
What are the most common side effects?
Dry mouth, trouble sleeping, restlessness, faster heartbeat, higher blood pressure, headache, dizziness, constipation or diarrhea, and an unpleasant taste.
Who should not take phentermine?
People with heart disease, uncontrolled high blood pressure, an overactive thyroid, glaucoma, a history of drug misuse, agitation, those who recently took an MAO inhibitor, and anyone who is pregnant or breastfeeding.
Related guides
- GLP-1 medications: how they work, benefits and side effects
- Wegovy pill in Utah: self-pay cost and how to start
- Zepbound without insurance: the real monthly cost
- GLP-1s for weight regain after bariatric surgery
- Virtual monitoring: smart scales, glucose and blood pressure
- Medical Weight Loss program overview
- All self-pay prices
- Primary care for our weight-loss patients
- Browse all patient guides
Reviewed by a fellowship-trained physician at Restoration Health Medical Group. Last updated October 2026. This page is general information, not medical advice for you; whether a medication is right for you is decided at your visit. For a medical emergency, call 911.