Key takeaways:
While newer, injectable weight-loss medications have attracted a lot of attention, they’re not the only options. Phentermine (Adipex-P, Lomaira) is one of the oldest medications approved for weight management in the U.S.
Insurance plans don’t always cover weight-loss medications. Most commercial plans not purchased through an Affordable Care Act (ACA) marketplace cover phentermine, and about half of Medicaid plans do. Some ACA plans cover phentermine, but almost every Medicare plan does not.
Phentermine, which is available in tablets or capsules, is one of the most affordable weight-loss medications. Without insurance, a 30-day supply of 37.5 mg tablets costs an average of $37.13. You could pay as little as $10.57 with a GoodRx coupon at select pharmacies. Brand-name options typically cost more.
Prescription weight-management injections such as Wegovy (semaglutide) and Zepbound (tirzepatide) are getting all the headlines right now. But weight-loss medications are not new. In fact, there are a number of effective and far less costly prescription weight-loss treatments — including pills — that have been around for decades. One of those legacy medications is phentermine (Adipex-P, Lomaira).
How much does phentermine cost without insurance?
Without insurance, what you pay for phentermine depends on several factors, including your:
Pharmacy
Location
Fill quantity
Medication dose
Dosage form
Search and compare options
Here are average retail prices for a 30-day supply of different doses of phentermine and brand-name alternatives, including Lomaira, which is typically taken 3 times daily.
Phentermine Costs
Phentermine form and dose | Average retail price |
30 capsules (15 mg) | |
30 capsules (30 mg) | |
30 capsules (37.5 mg) | |
30 tablets (37.5 mg) |
Costs for Phentermine Alternatives
Brand-name alternative and dose | Average retail price |
Adipex-P, 30 tablets (37.5 mg) | No price available |
Lomaira, 30 tablets (8 mg) | |
Lomaira, 90 tablets (8 mg) |
Note: Phentermine is a controlled substance, and some states will not allow you to use coupons on a controlled substance. So you may not be able to get the GoodRx discount in those places.
Is phentermine covered by insurance?
Some health insurance plans cover phentermine. Nearly all commercial plans not purchased through an Affordable Care Act (ACA) marketplace and about half of Medicaid plans cover this medication.
If you have insurance, review your plan’s summary of benefits and coverage and formulary (list of covered medications) to determine whether phentermine or a brand-name alternative is covered. If not, contact your plan provider and ask about your coverage options. You can also discuss alternatives with your prescriber or a pharmacist.
How insurance covers phentermine
The following charts show the likelihood of having coverage for phentermine 37.5 mg tablets and capsules with different types of insurance plans. They also show the likelihood of having prior authorization and step therapy requirements.
To get coverage for phentermine, some health insurance plans require enrollees to get prior authorization, and a few Medicaid plans require enrollees to do step therapy. In fact, prior authorization is required for about 1 in 3 people covered by a Medicaid plan.
Insurance Coverage for Phentermine (37.5 mg tablets)
Insurance type | Enrollees covered for phentermine 37.5 mg tablets | Enrollees required to get prior authorization | Enrollees required to do step therapy |
Commercial plans (not including plans purchased through an ACA marketplace) | 90% | 16.3% | 0% |
27.5% | 11% | 0% | |
Medicare, including original Medicare and Medicare Advantage plans | 3% | 2.2% | 0% |
Medicaid, including state-run and managed care plans | 51.2% | 36% | 2.1% |
Source: Managed Markets Insight & Technology, LLC™, as of May 12, 2025. (See methodology below.)
Insurance Coverage for Phentermine (37.5 mg capsules)
Insurance type | Enrollees covered for phentermine 37.5 mg capsules | Enrollees required to get prior authorization | Enrollees required to do step therapy |
Commercial plans (not including plans purchased through an ACA marketplace) | 90.4% | 16.2% | 0% |
46.5% | 29.5% | 0% | |
Medicare, including original Medicare and Medicare Advantage plans | 3% | 2.2% | 0% |
Medicaid, including state-run and managed care plans | 46.5% | 34.6% | 2.1% |
Source: Managed Markets Insight & Technology, LLC™, as of May 12, 2025. (See methodology below.)
Tips if your medication isn’t covered by insurance
If your insurance doesn’t cover phentermine, you still have options:
Use a GoodRx coupon to save on your prescription.
Ask your prescriber about less costly options that meet your needs. This could mean switching to another low-cost, generic medication.
Request a formulary exception from your insurance company. If your request is denied, you have the right to file an appeal with your plan.
When it’s time for open enrollment, compare different health insurance plans to find one that provides the coverage you need.
Phentermine interactions: It’s best not to take phentermine with antidepressants, alcohol, or stimulants, including caffeine or nicotine, to avoid interactions.
Side effects of phentermine: Phentermine can cause many side effects, including dry mouth and trouble sleeping — the most common — and headaches, tremors, or sexual changes.
Your phentermine questions, answered: Find out how phentermine works to help you lose weight, how long you can take it, and why it’s not the same as the discontinued “fen-phen” of the 1990s.
Where can I buy phentermine at an affordable price?
The cost of phentermine is much less than what you’d pay for many other weight-loss medications. Using GoodRx coupons can help you pay the lowest price.
The manufacturer of Lomaira offers a savings card that brings the price down to less than 50 cents per pill. The Adipex-P savings card program was discontinued on February 1, 2024.
What is phentermine?
Phentermine is an oral medication prescribed for weight loss in people ages 17 and older who have a body mass index (BMI) of at least 30 (or 27 with certain risk factors, including high blood pressure, diabetes, or high cholesterol).
Phentermine is the generic version of Adipex-P and Lomaira — two brand-name medications with the same active ingredient. Qsymia is a combination of phentermine and topiramate. It is also prescribed for weight loss.
Phentermine is a stimulant that was approved for use in the U.S. in 1959. At that time, the medication was recommended for short-term use — less than 12 weeks — along with behavioral changes like increased exercise and reduced calorie intake. Studies show that long-term use likely causes no major issues and is more likely to result in lasting weight loss.
By late 2023, the use of weight-loss pills, including phentermine, had risen markedly due to shortages of the newer injectable medications.
How is it taken?
Phentermine is taken orally via capsules or tablets. The medication comes in three once-daily doses: 15 mg, 30 mg, and 37.5 mg. Lomaira comes as an 8 mg tablet that’s taken 3 times a day. It’s recommended to take the lowest dose that is effective for you. Phentermine is considered a controlled substance, which means it comes with a risk of dependence and misuse.
How does phentermine work?
Phentermine suppresses your appetite. It helps you feel like you’re full, even if you're not. Some people report that phentermine also provides an energy boost. As a result, you may eat less and exercise more — two main behavioral changes that help with weight loss.
Frequently asked questions
Yes, you must have a prescription from a healthcare professional to get phentermine.
Ozempic (semaglutide) is approved by the FDA to treat Type 2 diabetes. It’s not approved for weight loss, but it is prescribed off-label for this purpose. Ozempic and phentermine work in different ways, but they can both decrease your appetite and result in weight loss. Phentermine, which can increase heart rate and blood pressure, is not recommended for people with heart disease. Ozempic may be a safer option than phentermine if you have heart disease, because the active ingredient, semaglutide, has proven to have cardiovascular benefits for people with heart disease — whether they have diabetes or not.
Phentermine can interact with an array of other substances and medications. You should avoid taking phentermine with stimulants, including caffeine and nicotine, as well as antidepressants and alcohol. It’s also best not to combine other weight-loss medications with phentermine unless this is recommended by your healthcare professional. Also, phentermine isn’t recommended if you have a history of heart problems, including stroke, a heart rhythm condition, or heart failure.
Yes, you must have a prescription from a healthcare professional to get phentermine.
Ozempic (semaglutide) is approved by the FDA to treat Type 2 diabetes. It’s not approved for weight loss, but it is prescribed off-label for this purpose. Ozempic and phentermine work in different ways, but they can both decrease your appetite and result in weight loss. Phentermine, which can increase heart rate and blood pressure, is not recommended for people with heart disease. Ozempic may be a safer option than phentermine if you have heart disease, because the active ingredient, semaglutide, has proven to have cardiovascular benefits for people with heart disease — whether they have diabetes or not.
Phentermine can interact with an array of other substances and medications. You should avoid taking phentermine with stimulants, including caffeine and nicotine, as well as antidepressants and alcohol. It’s also best not to combine other weight-loss medications with phentermine unless this is recommended by your healthcare professional. Also, phentermine isn’t recommended if you have a history of heart problems, including stroke, a heart rhythm condition, or heart failure.
The bottom line
Phentermine (Adipex-P, Lomaira) is one of the most affordable oral weight-loss medications. Available in tablets and capsules, phentermine has proven effective for decades.
How much you’ll pay for phentermine depends on factors such as your dosage form, pharmacy, and insurance coverage. If you don’t have insurance, a 30-day supply of 37.5 mg tablets costs an average of $37.13. You could pay as little as $10.57 with a GoodRx coupon at select pharmacies. Brand-name options often cost more.
If you have insurance but your plan doesn’t cover this medication, you could still save money by using a GoodRx coupon. Keep in mind that since phentermine is a controlled substance, your state’s regulations may not allow the use of discount cards on your prescription.
Why trust our experts?
Methodology
We obtained national prescription coverage data for each medication from Managed Markets Insight & Technology (MMIT). The data reflects health insurance coverage as of May 2025.
We calculated the percentage of enrollees in plans that cover each medication by dividing the number of enrollees covered for the medication within a specific insurance channel (e.g., ACA, Medicare, Medicaid) by the total number of enrollees in all plans within that channel.
We determined the percentage of enrollees in plans with a prior authorization requirement by calculating the proportion of enrollees in plans that required prior authorization for the medication within each channel.
Finally, we measured the percentage of enrollees in plans with a step therapy requirement by calculating the proportion of enrollees in plans that imposed step therapy requirements for the medication in each channel.
These estimates, derived from national MMIT coverage data, provide insight into health insurance coverage for each medication. They take into account restrictions such as prior authorization, step therapy, and quantity limits. The percentages are expressed relative to the total number of enrollees covered by various insurance channels, including the ACA, commercial (excluding ACA) plans, Medicare, and Medicaid (both state-run and managed care plans).
References
KVK Tech. (n.d.). The Lomaira Lo-Cost Access Program.
Lewis, K. H., et al. (2019). Safety and effectiveness of longer-term phentermine use: Clinical outcomes from an electronic health record cohort. Obesity.
Medicaid.gov. (n.d.). Managed care.
National Institute of Diabetes and Digestive and Kidney Diseases. (2020). Phentermine. LiverTox: Clinical and Research Information on Drug-Induced Liver Injury.
Tirrell, M. (2023). CNN exclusive: Older weight loss drugs are making a comeback as Zepbound, Wegovy remain out of reach for many. CNN Health.
