Comprehensive medication guide to Phentermine including estimated pricing, availability information, side effects, and how to find it in stock at your local pharmacy.
Estimated Insurance Pricing
$0–$30 copay if covered; many plans exclude weight-loss drugs or require prior authorization.
Estimated Cash Pricing
$10–$40/month for generic Phentermine 37.5 mg with GoodRx or SingleCare coupons; up to $75 without a discount card.
Medfinder Findability Score
75/100
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Phentermine is a prescription appetite suppressant approved by the FDA for the short-term treatment of obesity. It belongs to a class of drugs called sympathomimetic amines and has been available since 1959, making it one of the oldest and most widely prescribed weight-loss medications in the United States. Phentermine is indicated for patients with a BMI of 30 or greater, or 27 or greater with at least one weight-related condition such as high blood pressure, type 2 diabetes, or high cholesterol. It is intended to be used alongside a reduced-calorie diet, exercise, and behavioral changes. Treatment is typically limited to up to 12 weeks, although many physicians prescribe it for longer periods based on clinical judgment.
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Phentermine works by stimulating the release of norepinephrine in the brain, particularly in the hypothalamus — the region that controls appetite. This triggers a fight-or-flight response that reduces hunger signals and increases energy expenditure. Phentermine may also modestly increase dopamine and serotonin levels. The combined effect suppresses appetite, making it easier for patients to stick to a calorie-restricted diet. Because Phentermine is a stimulant, it also provides a mild energy boost, which can help patients stay active during weight loss.
Phentermine 37.5 mg tablets
most commonly prescribed, taken once daily
Phentermine 15 mg capsules
lower dose option, taken once daily
Phentermine 30 mg capsules
once daily dosing
Phentermine 8 mg tablets (Lomaira)
taken three times daily, 30 minutes before meals
Adipex-P 37.5 mg tablets and capsules
brand-name equivalent of generic 37.5 mg
Phentermine is generally available at most pharmacies, earning a findability score of 75 out of 100. As a widely prescribed generic, it is stocked by the majority of retail and chain pharmacies. However, because Phentermine is a Schedule IV controlled substance, DEA manufacturing quotas can occasionally limit supply. Some patients have reported intermittent difficulty finding specific strengths (particularly 15 mg capsules) at their local pharmacy since 2022, driven partly by the overall surge in demand for weight-loss medications. Phentermine is not currently listed on the FDA Drug Shortage database. If your pharmacy is out of stock, try calling nearby pharmacies or use Medfinder to locate availability near you.
Phentermine can be prescribed by any licensed physician or qualified healthcare provider with DEA prescribing authority for Schedule IV substances. The most common prescribers include:
Phentermine is also available through many telehealth platforms, making it convenient to obtain a prescription without an in-person visit in most states.
Yes, Phentermine is classified as a Schedule IV controlled substance by the DEA. This means it has a recognized medical use but carries a low-to-moderate potential for physical or psychological dependence. As a controlled substance, Phentermine prescriptions are subject to DEA manufacturing quotas, which can occasionally contribute to supply limitations. Refills may be restricted depending on state law, and some states require in-person visits for initial or ongoing prescriptions. Always obtain Phentermine only with a valid prescription from a licensed provider.
Rare but serious side effects include primary pulmonary hypertension, heart valve problems, chest pain, and shortness of breath. Contact your doctor immediately if you experience any of these symptoms. Phentermine may also cause dependence with prolonged use.
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Qsymia (Phentermine/Topiramate ER)
a combination pill that pairs Phentermine with Topiramate for enhanced weight loss; available only through certified pharmacies
Contrave (Naltrexone/Bupropion)
a non-stimulant, non-controlled oral medication for chronic weight management
Orlistat (Xenical/Alli)
blocks fat absorption in the gut; Alli is available over the counter at a lower dose
Wegovy (Semaglutide)
a once-weekly GLP-1 injection approved for weight management; highly effective but expensive
Saxenda (Liraglutide)
a daily GLP-1 injection for weight loss
Zepbound (Tirzepatide)
a once-weekly dual GLP-1/GIP injection for obesity; among the most effective options available
Prefer Phentermine? We can find it.
MAO inhibitors
moderatedo NOT take Phentermine within 14 days of an MAO inhibitor; this combination can cause a dangerous hypertensive crisis
Other stimulants and sympathomimetic amines
moderateincreased risk of cardiovascular side effects
SSRIs, SNRIs, and triptans
moderaterisk of serotonin syndrome when combined with Phentermine
Antihypertensive medications
moderatePhentermine may reduce the effectiveness of blood pressure drugs
Insulin and oral diabetes medications
moderateweight loss may change blood sugar levels, requiring dose adjustments
Alcohol
moderatemay worsen dizziness and CNS side effects
Phentermine remains one of the most affordable and accessible prescription weight-loss medications on the market. With generic versions widely available for as little as $10–$40 per month, it offers a cost-effective option for patients who qualify. While it is not currently in shortage, occasional spot shortages can occur due to DEA manufacturing quotas and the growing demand for weight-loss treatments. If you're having trouble finding Phentermine at your local pharmacy, Medfinder can help you locate pharmacies with current stock near you. Always use Phentermine under the supervision of a healthcare provider, and discuss the full range of weight-management options to find the best fit for your needs.
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