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Get Phentermine online prescription

In a retrospective study, 62% of patients taking phentermine for weight loss lost at least 3% of their starting body weight in 12 weeks. If you weigh 200 pounds, that’s 6 pounds!

Is phentermine the right weight loss medication for you? Find a weight loss specialist to find out. If it is, get a phentermine online prescription in as little as 24 hours.

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Medically reviewed by: Dr. Sheelu Bhatnagar

What is phentermine?

Phentermine is an oral weight loss drug originally U.S. Food and Drug Administration (FDA)-approved in 1959 as an appetite-suppressant. Its current form, phentermine hydrochloride, has been available since 1973. It’s approved for weight loss over 3 months when used with a reduced-calorie diet and increased physical activity. 

Phentermine is a generic medication and the active ingredient in brand-name Lomaira and Adipex-P. It’s also 1 of 2 active ingredients in Qsymia (phentermine-topiramate).

What sets phentermine apart from other weight loss drugs is that it’s only meant to be used for up to 3 months. Other weight loss meds are approved for long-term use.

Studies though show that long-term use of phentermine is safe and results in greater weight loss. And some providers prescribe it off-label for longer-term use.

How does phentermine work for weight loss?

Phentermine is an appetite suppressant and central nervous system (CNS) stimulant. It works by increasing the levels of serotonin, noradrenaline, and dopamine. which help transmit signals in the brain, muscles, and glands in your body. The effect of these added neurotransmitters may stimulate feelings of fullness or satiety, which suppresses appetite, boosts energy levels, and breaks down stored fat, which leads to weight loss.

In retrospective studies, people taking phentermine short-term lost at least 3% of their body weight in 12 weeks.

Who can take phentermine?

Phentermine is FDA-approved for people 17 and older who: 


— Have obesity, which means a body mass index (BMI) of 30 or more.

— Are overweight and have a BMI of 27 or more and at least one weight-related health problem, like high blood pressure, type 2 diabetes, heart problems, or high cholesterol.


If you take it, you should eat less and exercise more.


Find a provider to talk about a phentermine online prescription

How to get a phentermine online prescription

Getting phentermine online starts with getting a prescription. A trained, licensed healthcare provider can prescribe phentermine or another weight loss medication if they recommend it for you. Providers who can prescribe medications include physicians (MDs), physician assistants/associates (PAs), or ​​nurse practitioners (NPs).

On Klarity, find a board-certified, licensed provider and have an initial appointment online. Your provider will help you develop a medical weight loss program that may include medication, such as phentermine. If your provider gives you a prescription, you can get phentermine at any pharmacy that has it in stock, local or online.

Phentermine dosages

Generic phentermine and Adipex-P come in 15-, 30-, and 37.5-milligram tablets or capsules you take by mouth. The usual dose is 1 tablet or capsule before breakfast or 1 to 2 hours after breakfast. 

Lomaira comes in 8-milligram tablets. One-half or one tablet is taken 30 minutes before meals 3 times a day.

Your provider may prescribe half a tablet (18.75 milligrams) in the morning or twice a day, depending on how you tolerate phentermine. They’ll have you take the lowest dose that works for you, which may be up to 37.5 milligrams.

Note that you don’t want to take phentermine at night because it can cause insomnia. 

Phentermine side effects and warnings

Phentermine doesn’t have any known common side effects. Adverse reactions have been reported with phentermine use though, including high blood pressure, valvular heart disease, fast heartbeat, restlessness, insomnia, psychosis, tremor, headache, dry mouth, diarrhea, constipation, and impotence.

Tell your healthcare provider about any existing health problems you have before taking phentermine, including drug abuse or are taking or have taken monoamine oxidase inhibitors (MAOIs) in the last 14 days. And if you have any adverse reactions while taking phentermine, tell your provider right away.

What does phentermine cost?

Generic phentermine costs around $12 for a 1-week supply (7 pills), or roughly $48 per month, according to drugs.com and with their discount card. 

If you get brand-name Adipex-P, it costs about $76 for a 1-month supply. Lomaira costs around $64 per 1-month supply. 

With health insurance coverage, you may pay less. You can also save on phentermine with coupons from drug discount sites like SingleCareRx, drugs.com, GoodRx, WellRx, and others. 

If you choose a brand name, you may be eligible to save on Adipex-P with Teva Pharmaceuticals’ Adipex-P Prescription Savings Program. You can also save on Lomaira with a coupon from the manufacturer, KVK-Tech.

How does phentermine compare to other weight loss medications

You’ll lose less weight on phentermine than on newer weight loss drugs. Retrospective studies show you can lose at least 3% of your body weight in 12 weeks with phentermine. People taking glucagon-like peptide-1 (GLP-1) agonist medication Wegovy (semaglutide) for weight loss lose up to 14.9% of their starting body weight in 68 weeks. Those taking dual GLP-1/glucose-dependent insulinotropic polypeptide (GIP) agonist drug Zepbound (tirzepatide) lose up to 20.9% of their body weight in 52 weeks. 

Only you and your healthcare provider can decide which weight loss medication, if any, is right for you. 
Learn more about weight loss with Wegovy vs phentermine.



Doctor comparing phentermine for weight loss to other drugs

On Klarity, you’re in good company

Read through stories from real patients who received treatment from healthcare providers on Klarity.

How it works

  1. Choose the right provider for you

    Providers on Klarity are licensed, board-certified, and offer a personalized approach to your unique weight-loss needs. See detailed profiles for each provider and find an approach that’s best for you. (Costs for treatment options may vary.)

  2. Have your initial patient visit

    Your journey to losing weight starts with an initial consultation Your provider will go over your goals and medical history to recommend a program that’s right for you and may or may not include prescription medication.

  3. Work with your provider on your progress 

    Your initial consultation is just the beginning. You and your provider will follow up to make sure you’re doing okay and that you’re reaching your goals. You stay on track with easy medication refills and ongoing support from your provider.

  4. Get constant support from Klarity

    If you have questions or need assistance, the Klarity Patient Support team is here to help. Along with your provider, they’re committed to making sure you have the best care and support throughout your weight loss journey.

Why choose a provider on Klarity?

Choose from a growing list of licensed, board-certified providers.

Choose from a growing list of licensed, board-certified providers.


Have an appointment in as little as 24 hours.

Have an appointment in as little as 24 hours.


No insurance needed — 
get reimbursed from insurance or use your FSA or HSA.

FAQs about phentermine

Are there brand-name drugs with active ingredient phentermine?

Yes, Adipex-P and Lomaira are brand-name drugs with the active ingredient phentermine. Both are FDA-approved for weight loss in people with a BMI of 30 or greater, or 27 or greater with other risk factors. They’re meant for short-term use — up to a few weeks. 

Phentermine is also 1 of 2 active ingredients in the brand-name drug Qsymia. It’s approved for the same patient population as Adipex-P and Lomaira but can be used long-term. 

Does insurance cover phentermine?

It depends. Many insurance companies don’t cover weight loss medications, including phentermine. If your plan covers phentermine, you likely need prior authorization. While phentermine isn’t a new or expensive drug, it’s been linked to safety concerns in the past. 

In the 1990s, serious safety issues were associated with fenfluramine-phentermine (or fen-phen), a popular weight loss drug cocktail. Fenfluramine was taken off the market as a result. Research shows that phentermine alone is safe and it’s never been taken off the market. Yet, insurance companies act out of an abundance of caution and often won’t cover it without prior authorization, which includes a medical record review. 

Contact your insurer to find out if phentermine is covered and if you need prior authorization. If you’re denied, work with your provider to appeal a prior authorization denial.

How long does it take to lose weight on phentermine?

Reddit users who’ve taken phentermine say they lose weight fairly quickly — some report up to 5 pounds in 1 week. In clinical studies, people taking phentermine lost at least 3% of their starting body weight in 3 months. If you’re prescribed phentermine for longer, you could lose even more. In an older study, people who took phentermine for 36 weeks lost at least 13% of their initial body weight. 

How long do phentermine side effects last?

Phentermine’s common side effects tend to subside as your body gets used to it — usually within a few days or weeks. Tell your healthcare provider if your side effects persist or interfere with your daily life. This may be a sign that phentermine isn’t working for you. Your provider will address your symptoms and, if needed, lower your dose or suggest alternatives. 

Can you switch from phentermine to a GLP-1 agonist medication?

Yes, you can switch from phentermine to a GLP-1 agonist medication, and vice versa. Switching may help you maintain weight loss and lose more weight. Evidence suggests if you switch from a GLP-1 drug to phentermine, you’re less likely to experience rebound weight gain. As far as switching from GLP-1 to phentermine, in clinical studies, people who lost less than 20 pounds with a GLP-1 drug and switched to phentermine lost an additional 3% body weight in the year following the switch. 

When switching between phentermine and a GLP-1, your provider may add 1 to the other. Not only does this help your body adjust — research shows that using phentermine in combination with a GLP-1 drug can result in greater weight loss. If you’re thinking about switching from phentermine to a GLP-1 drug, or vice versa, consult your provider. 

How to quickly buy phentermine online without insurance? 

You can get phentermine online with or without insurance. To get a prescription quickly, and without insurance, find an online provider on Klarity. It’s a marketplace platform that connects you with a board-certified, licensed healthcare provider in virtual appointments. When you find a provider on Klarity, you can have an appointment and get a prescription for phentermine, if recommended, in 24 hours or less and without insurance. 

How long can you stay on phentermine?

You can stay on phentermine for up to 12 weeks as it’s only approved for short-term use. Ongoing research suggests that long-term use is safe and results in greater weight loss. In clinical studies, people who took phentermine continuously for 1 year lost 7.5% more body weight than those who didn’t. 

Talk to your healthcare provider about how long you can safely stay on phentermine. They can prescribe it long-term if they feel the benefits outweigh the risks in your case. Note that long-term use is off-label (unapproved), so getting insurance to cover your prescription may be more difficult.

Do you need a doctor’s prescription for phentermine?

Yes, you need a doctor’s prescription for phentermine. Your prescription must be valid and from a board-certified, licensed healthcare provider. Use your current provider or find one on Klarity and have an online appointment to discuss weight loss medication in 24 hours or less.

What happens after 3 months of phentermine?

After 3 months on phentermine, your provider will gradually taper your dosage to prevent unwanted symptoms, like fatigue, drowsiness, tremors, and depression. Research shows that phentermine isn’t addictive — any symptoms you experience after stopping are due to no longer having it in your system. As your body adjusts, symptoms tend to reside. For this reason, stopping phentermine abruptly isn’t recommended. Talk to your provider about how to stop phentermine safely.

If your provider feels it’s medically necessary, they can prescribe phentermine for longer than 3 months. This is an off-label use, but clinical evidence suggests you could lose more weight. 

Is Ozempic better than phentermine?

Everyone responds to medication differently, so it’s hard to say whether Ozempic for weight loss is better than phentermine. They’re also in different drug classes and work differently. You can lose more weight on Ozempic — potentially more than 10% of your body weight. You can also take it long-term whereas phentermine is only approved for short-term use (up to 12 weeks). Most people who take phentermine lose about 3% body weight, sometimes more. Greater weight loss is possible with phentermine if you take it long-term, but this is an off-label use. 

If you’re comparing cost, Ozempic is more expensive than phentermine. Without insurance, you’ll pay more than $1,000 per month for Ozempic. Generic phentermine retails for as little as $12, according to drugs.com and with its discount card. You’ll pay less with insurance. You’ll likely need prior authorization for either medication.

Sources
American Journal of Therapeutics, A study of abrupt phentermine cessation in patients in a weight management program, Ed J. Hendricks & Frank L. Greenway, Jul. 2011, https://pubmed.ncbi.nlm.nih.gov/20592662/

DailyMed, Label: Adipex-P-phentermine hydrochloride tablet, Adipex-P-phentermine hydrochloride capsule, https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=f5b2f9d8-2226-476e-9caf-9d41e6891c46

DailyMed, Label: Lomaira- phentermine hydrochloride tablet, https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=cde9fb09-e5af-434d-8874-e4f9f974d893

DailyMed, Label: Ozempic-semaglutide injection solution, https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=adec4fd2-6858-4c99-91d4-531f5f2a2d79

DailyMed, Label: Phentermine hydrochloride tablet, capsule, https://dailymed.nlm.nih.gov/dailymed/lookup.cfm?setid=3b44d104-a7d0-4366-9d42-63f784f3cb22

DailyMed, Label: Qsymia- phentermine and topiramate capsule, extended release, https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=40dd5602-53da-45ac-bb4b-15789aba40f9

Diabetes, Metabolic Syndrome, and Obesity, Clinical utility of phentermine/topiramate (Qsymia) combination for the treatment of obesity, Jin Hee Shin and Kishore M. Gadde, Apr. 2013, https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3626409/

drugs.com, Adipex-P Price Guide, https://www.drugs.com/price-guide/adipex-p&sa=u&

drugs.com, Lomaira Price Guide, https://www.drugs.com/price-guide/lomaira

drugs.com, Ozempic price guide, https://www.drugs.com/price-guide/ozempic

drugs.com, Phentermine Price Guide, https://www.drugs.com/price-guide/phentermine

Epic Research, Patients who lose less than 20 pounds on GLP-1 treatment lose more weight after switching to phentermine, Kersten Bartelt, RN, et al., May 2024, https://www.epicresearch.org/articles/patients-who-lose-less-than-20-pounds-on-glp-1-treatment-lose-more-weight-after-switching-to-phentermine

International Journal of Clinical Pharmacology and Therapeutics, Three- and six-month efficacy and safety of phentermine in a Mexican obese population, Maribel Márquez-Cruz et al., Aug. 2021, https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8295716/

JCEM Case Reports, Weight loss from combination anti-obesity medication regimens can approach that achieved from bariatric surgery, Priya N. Patel et al., Jan. 2023, https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10578411/

KFF Health News, Many Insurers Do Not Cover Drugs Approved to Help People Lose Weight, Michelle Andrews, Jan. 2015, https://kffhealthnews.org/news/many-insurers-do-not-cover-drugs-approved-to-help-people-lose-weight/

KVK Tech, Inc., Lomaira, https://lomaira.com/?gad_source=1&gclid=CjwKCAjwvIWzBhAlEiwAHHWgvdNm7nz84vhZkjZJxYe3yuyUHujHR7yG8jx_TMsJSmVT7clEO8yMKBoCpqgQAvD_BwE

Metabolism, Effects of liraglutide plus phentermine in adults with obesity following 1 year of treatment by liraglutide alone: A randomized, placebo-controlled pilot trial, Jena Shaw Tronieri, Ph.D. et al., Jul. 2019, https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6571049/

National Library of Medicine, Pharmacologic Treatment of Overweight and Obesity in Adults, Beverly G. Tchang, MD, Mohini Aras, MD, Rekha B. Kumar, MD, MS, and Louis J. Aronne, MD., Aug. 2021, https://www.ncbi.nlm.nih.gov/books/NBK279038/

Obesity — A Research Journal, Safety and Effectiveness of Longer-Term Phentermine Use: Clinical Outcomes from an Electronic Health Record Cohort, Kristina H. Lewis et. al., Mar. 2019, https://onlinelibrary.wiley.com/doi/10.1002/oby.22430

Obesity Medicine Association, Does Insurance Cover Weight Loss Medication?, Dec. 2023, https://obesitymedicine.org/blog/does-insurance-cover-weight-loss-medication/

Obesity Research, The fen-phen finale: a study of weight loss and valvular heart disease, T.A. Wadden et al., Jul. 1998, https://pubmed.ncbi.nlm.nih.gov/9688104/

Reddit.com, Phentermine, https://www.reddit.com/r/loseit/comments/14xoh5a/phentermine/

ScienceDirect, Phentermine: from Progress in Cardiovascular Diseases, 2018, https://www.sciencedirect.com/topics/medicine-and-dentistry/phentermine

Teva Pharmaceuticals, Adipex-P Prescription Savings Program, https://www.adipex.com/globalassets/adipex/adipex-p-digital-copay-program.pdf

The information provided in this article is for educational purposes only and should not be construed as medical advice. Everyone’s weight loss journey is unique and results will vary. Always seek the guidance of a qualified healthcare professional with any questions or concerns you have regarding your health.

How we reviewed this article: This article goes through rigorous fact-checking by a team of medical reviewers. Reviewers are trained medical professionals who ensure each article contains the most up-to-date information, and that medical details have been correctly interpreted by the author.

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All professional services are provided by independent private practices via the Klarity technology platform. Klarity Health, Inc. does not provide any medical services.
Fax:
(855) 975-3008

PO Box 5098 Redwood City, CA 94063

100 Broadway Street, Redwood City CA, 94063

logo
All professional services are provided by independent private practices via the Klarity technology platform. Klarity Health, Inc. does not provide any medical services.
If you’re having an emergency or in emotional distress, here are some resources for immediate help: Emergency: Call 911. National Suicide Prevention Hotline: Call 988. Crisis Text Line: Text Home to 741-741
Fax:
(855) 975-3008

PO Box 5098 Redwood City, CA 94063

100 Broadway Street, Redwood City CA, 94063

If you’re having an emergency or in emotional distress, here are some resources for immediate help: Emergency: Call 911. National Suicide Prevention Hotline: Call 988. Crisis Text Line: Text Home to 741-741
© 2024 Klarity Health, Inc. All rights reserved.