Medically reviewed by Austin Ulrich, PharmD
Key Takeaways
- Phentermine is an FDA-approved prescription medication used for short-term weight management combined with diet and exercise.
- Common side effects include increased heart rate, insomnia, and dry mouth; it is generally not recommended for individuals with a history of heart disease or uncontrolled high blood pressure.
- Phentermine is regulated as a controlled substance because it carries risks of misuse and dependence.
- Prescription discount programs like the Super+ RX coupon can help you save money on phentermine and other prescriptions.
Price Comparison Overview
Retail prices vary significantly by pharmacy location. Below is an estimated comparison of what you might expect to pay for a standard 30-day supply at a typical retail pharmacy versus using a savings program.
| Medication Type | Estimated Average Retail Price | Estimated Super+ RX Member Price |
| Phentermine (Generic) | ~$30.00 – $45.00 | ~$9.00 – $15.00 |
| Adipex-P (Brand) | ~$70.00 – $100.00+ | ~$60.00 – $90.00+ |
| Lomaira (Brand) | ~$40.00 – $70.00+ | $15.00 – $30.00+ |
What Is Phentermine?
Phentermine is a prescription medication primarily used as an appetite suppressant to promote weight loss. It belongs to a class of medications known as “anorectics” or “sympathomimetic amines.” In simpler terms, it acts on the central nervous system similarly to a stimulant, helping to reduce hunger cravings and make you feel full longer.
The FDA approved this medication in 1959 for short-term weight management. It is designed to be part of a comprehensive weight loss plan that includes nutritional changes, exercise, and behavior modification. It is not intended to be a standalone solution or a long-term maintenance treatment.
When you receive a prescription, you might see it written as the generic name “phentermine” or under brand names such as Adipex-P or Lomaira. Regardless of the name on the label, the active chemical ingredient designed to suppress appetite remains the same. Because of its chemical structure and potential for misuse, it is classified as a Schedule IV controlled substance in the United States, meaning its distribution is tightly regulated.
Dosage and Administration
This medication is typically prescribed for individuals with a body mass index (BMI) of 30 or higher (obesity) or a BMI of 27 or higher (overweight) if they also have weight-related conditions such as high blood pressure, diabetes, or high cholesterol.
Short-Term Use
Healthcare professionals typically prescribe phentermine for a limited period, usually up to 12 weeks. The body can build a tolerance to the appetite-suppressing effects over time, making phentermine less effective for long-term use. Consequently, it is intended to jump-start weight loss while you establish long-term healthy habits.
Forms and Strengths
The medication comes in various forms, including tablets and extended-release capsules.
- Tablets: Available in 8 mg or 37.5 mg doses.
- Capsules: Available in 15 mg, 30 mg, and 37.5 mg doses.
Phentermine is typically taken once daily, in the morning before breakfast or 1 to 2 hours after breakfast. Because it is a stimulant, taking it late in the day is generally discouraged as it may lead to trouble sleeping (insomnia).
Understanding Side Effects
Because phentermine stimulates the central nervous system, it affects more than just your appetite. Being aware of potential side effects helps you monitor your body’s reaction and communicate effectively with your healthcare professional.
Common Side Effects
Many individuals experience mild side effects as their body adjusts to the medication. These often include:
- Dry mouth: A frequent complaint that can be managed by increasing water intake or chewing sugar-free gum.
- Insomnia: Difficulty falling or staying asleep, particularly if the dose is taken too late in the day.
- Constipation: Changes in digestive patterns are common.
- Unpleasant taste: You may experience a metallic or bitter taste.
- Restlessness or dizziness: Feelings of over-stimulation or jitters.
Serious Adverse Effects
While less common, more severe reactions can occur. You should stop taking the medication and seek immediate medical attention if you experience:
- Heart issues: Chest pain, pounding heart, rapid heart rate, or significant increase in blood pressure.
- Shortness of breath: Even with mild exertion.
- Swelling: Specifically in the ankles or feet (edema).
- Severe mental changes: Extreme agitation, confusion, or hallucinations.
Who Should Avoid Phentermine?
This medication is not suitable for everyone. People with a history of heart disease, hyperthyroidism, glaucoma, or those with a history of medication use disorder are typically advised against using phentermine. As mentioned previously, phentermine is a controlled substance with risks of misuse and dependence.
Additionally, it can interact negatively with other medications, particularly monoamine oxidase inhibitors (MAOIs). Always provide your healthcare professional with a complete list of medications and supplements you are currently taking.
Brand Name vs. Generic: Analyzing the Cost
The brand-name versions, Adipex-P and Lomaira, contain the exact same active ingredient as generic phentermine. The FDA requires generic medications to have the same dosage, safety, strength, quality, and performance characteristics as the brand-name form. The primary difference is the cost.
How to Save on Your Phentermine Prescription
Here are several practical ways you can save money if you need a prescription for phentermine — whether you have insurance or not:
- Use a prescription discount card or coupon like Super+ RX: The Super+ RX coupon uncovers discounts to help lower out-of-pocket costs for phentermine. Whether it’s phentermine or another medication, we want to help you save—because your well-being comes first.
- Check multiple pharmacies — cash prices can vary. Pharmacies in the same area sometimes charge different prices for the same medication. Comparing cash prices among pharmacies can help you find the cheapest option. Search for your prescription on Super.com/rx, compare prices across pharmacies, and find discounts near you.
What you can do before you go to the pharmacy:
- Use a discount program like the Super+ RX coupon — print it or bring it on your phone — and ask the pharmacist or cashier to apply it to your prescription.
- Compare at least two or three pharmacies on Super.com/rx to see who offers the lowest price.
- If you are uninsured or if you have a high copay, ask your healthcare team about patient-assistance programs or reduced-cost clinics in your area.
We understand that managing chronic conditions often comes with concerns about the cost of medications. Whether you’re looking for phentermine 15 mg, phentermine 37.5 mg, or another dosage or a brand-name form, a few simple clicks can show you where to get your medication at a more affordable price.
Ready to save on phentermine? Compare prices for phentermine at pharmacies near you and start lowering your medication costs.
Frequently Asked Questions
Are there over-the-counter (OTC) alternatives to phentermine? No, there is no direct OTC equivalent to phentermine. While various supplements claim to suppress appetite, they are typically not evaluated in clinical studies or approved by the FDA. Phentermine is a regulated pharmaceutical that requires a prescription. Always consult a healthcare professional before trying OTC diet pills, as they are not regulated as strictly as prescription medications.
How long can I stay on this medication? It is approved for short-term use, typically up to 12 weeks. Extended use can increase the risk of dependence and side effects. If weight loss goals have not been met after this period, your healthcare professional may reassess your treatment plan.
Can I drink alcohol while taking this drug? It is strongly recommended to avoid alcohol while taking this medication. Alcohol can worsen side effects such as dizziness and confusion, and may worsen the medication’s effect on the central nervous system.
Does this medication burn fat directly? No. It works by suppressing appetite, which helps you eat fewer calories. Weight loss occurs because of the caloric deficit created by eating less and moving more, not because the medication itself dissolves fat.
References
Bays HE, Lazarus E, Primack C, Fitch A. Obesity pillars roundtable: Phentermine – Past, present, and future. Obes Pillars. 2022;3:100024. doi:10.1016/j.obpill.2022.100024
Johnson DB, Quick J. Topiramate and phentermine. StatPearls. March 27, 2023. Accessed February 6, 2026. https://www.ncbi.nlm.nih.gov/books/NBK482165/
Kenny BJ, Preuss CV, Zito PM. Controlled substance schedules. StatPearls. June 26, 2023. Accessed February 6, 2026. https://www.ncbi.nlm.nih.gov/books/NBK538457/
Phentermine hydrochloride capsule. Prescribing information. Market Pharmacal Co., 2026. Accessed February 6, 2026. https://nctr-crs.fda.gov/fdalabel/services/spl/set-ids/1149f69d-65df-6a98-e063-6394a90aeaa4/spl-doc
Phentermine hydrochloride tablet. Prescribing information. A-S Medication Solutions, 2026. Accessed February 6, 2026. https://nctr-crs.fda.gov/fdalabel/services/spl/set-ids/86ec6b9d-2934-4bad-8a80-0b60e2f912f3/spl-doc
Disclaimer:
Generative AI was used in the development of this content. All information in this article has been reviewed by our highly-trained clinicians. Under applicable law, pharmacies may decline to accept discount coupons for controlled substances at their own discretion. Discounts on controlled substances are not guaranteed.
We do not provide medical advice. Please, consult a physician.
