Can't find or fill your Phentermine prescription? Here are FDA-approved alternatives for weight loss, how they work, and what to ask your doctor about switching.
If you've been prescribed Phentermine and can't find it in stock — or if Phentermine isn't the right fit for you — there are several FDA-approved alternatives worth discussing with your doctor. Each works differently, and what's best for you depends on your health history, weight-loss goals, and budget.
In this guide, we'll explain what Phentermine is, how it works, and walk through the most common alternatives available in 2026.
Phentermine is one of the oldest and most widely prescribed weight-loss medications in the United States. It was first approved by the FDA in 1959 and remains popular because of its effectiveness and low cost.
Phentermine is a sympathomimetic amine — a type of stimulant that works in the brain to suppress appetite. It's classified as a Schedule IV controlled substance and is typically prescribed for short-term use (up to 12 weeks) alongside diet and exercise.
It's available as a generic and under brand names including Adipex-P and Lomaira. The most common dose is 37.5 mg taken once daily in the morning. Generic Phentermine is affordable, often costing between $10 and $40 per month with a discount card.
Phentermine stimulates the release of norepinephrine in the hypothalamus — the part of the brain that controls hunger signals. This triggers a mild "fight-or-flight" response that:
The effect is strongest in the first few weeks and tends to diminish over time, which is one reason it's approved for short-term use. Most patients lose between 5-10% of their body weight during a typical 12-week course when combined with lifestyle changes.
There are several reasons you might need a Phentermine alternative:
What it is: Qsymia is a combination medication that pairs a lower dose of Phentermine with topiramate, an anti-seizure drug that also reduces appetite and promotes satiety.
How it works: The phentermine component suppresses appetite through norepinephrine release, while topiramate works through GABA modulation and other mechanisms to reduce cravings and increase the feeling of fullness.
Key details:
Best for: Patients who responded well to Phentermine and want a longer-term option with enhanced effectiveness.
What it is: Contrave combines naltrexone (used for addiction treatment) with bupropion (an antidepressant and smoking-cessation aid) to target cravings and reward-driven eating.
How it works: Bupropion acts on the hypothalamus to reduce appetite, while naltrexone blocks opioid receptors involved in food reward pathways. Together, they reduce both hunger and the pleasure-driven urge to eat.
Key details:
Best for: Patients who struggle with food cravings or emotional eating, especially those who can't take stimulant medications.
What it is: Orlistat is a lipase inhibitor that works in the gut — not the brain — to block fat absorption.
How it works: It prevents your body from absorbing about one-third of the fat you eat. The unabsorbed fat passes through your digestive system.
Key details:
Best for: Patients who prefer a non-stimulant, non-centrally-acting medication, or who want an over-the-counter option.
What they are: These injectable medications mimic a gut hormone called GLP-1 that regulates appetite and blood sugar.
How they work: They slow gastric emptying, increase satiety signals to the brain, and reduce appetite — leading to significant, sustained weight loss.
Key options:
Key details:
Best for: Patients seeking significant weight loss who have insurance coverage or can afford the cost, especially those with type 2 diabetes or cardiovascular risk factors.
Here's a quick comparison to help frame the conversation with your doctor:
Phentermine is a great medication for many patients, but it's not the only option. Whether you can't find it in stock, experience side effects, or need a longer-term solution, there are several FDA-approved alternatives worth exploring.
The most important step is talking to your doctor. They can help you weigh the benefits, side effects, costs, and availability of each option and find the best fit for your situation.
And if you're still looking for Phentermine, don't give up — check Medfinder first. It might be in stock just down the road.
Related reading:
You focus on staying healthy. We'll handle the rest.
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