Skip to main content
Medically Approved

Phentermine oral forms dosage: A detailed guide

twitter share buttonfacebook share buttonlinkedin share buttonemail article button
Forms and strengthsDosageFAQsHow it’s takenCouponOverdoseAsk your doctor
Doctors prescribe phentermine oral forms for weight loss in certain adults. These adults have obesity or are overweight. You take the oral forms by mouth once or twice per day.
Medically reviewed by Dena Westphalen, PharmD
Updated on

Phentermine oral forms are generic versions of the brand-name drugs Lomaira and Adipex-P.

This article describes phentermine oral forms’ dosages, their strengths, and details on how to take them. You’ll also find information on cost savings and coupon options for phentermine.

If you want to know more about phentermine oral forms, see this overview article. It covers details about the drug’s uses, side effects, ways to save on cost, and more.

Forms and strengths of phentermine

Phentermine oral forms come as follows:

Forms and strengths:

  • capsule that you swallow: 15 milligrams (mg), 30 mg, 37.5 mg
  • tablet that you swallow: 8 mg, 37.5 mg
  • orally disintegrating tablet (ODT) that dissolves on or under your tongue: 15 mg, 30 mg, 37.5 mg

Dosage of phentermine

This article describes the recommended dosages* for phentermine oral forms.

If your doctor prescribes this medication, you should take the dosage they prescribe. Your doctor will determine the dosage that best meets your needs. Do not change your dosage of phentermine oral forms without your doctor’s recommendation.

* The drug manufacturer provides these recommended dosages.

Usual recommended dosages of phentermine in adults

Usually, doctors start by prescribing a low dosage of phentermine oral forms. Then, they’ll adjust it over time until the right dosage is reached. Ultimately, your doctor will prescribe the smallest dosage of phentermine oral forms that gives the desired outcome.

Dosage for weight loss

The following dosage for weight loss is in milligrams (mg).

  • Dose: 8 mg to 37.5 mg
  • Frequency: one to three times per day
  • Maximum dosage: 37.5 mg per day

Dosage adjustments for phentermine

Your doctor will prescribe a dosage of phentermine oral forms based on certain factors. These include other health conditions you may have, such as kidney failure.

Man on phone in bed

100% online care

Treatment plans in 15 minutes or less for 40+ conditions.

Start consult now

Missed dose of phentermine

Talk with your doctor or pharmacist right away if you realize you forgot to take a dose of phentermine oral forms. They may advise you to take the missed dose. Or they may advise you to skip it and take your next dose as scheduled.

For tips on how to plan your doses of phentermine oral forms and avoid missing a dose, read this article. You could also try:

  • downloading a reminder app on your phone
  • setting an alarm
  • putting a note where you’ll see it, such as on your calendar, bathroom mirror, or bedside table

Frequently asked questions

Below are answers to some commonly asked questions about phentermine oral forms and its dosage.

Does phentermine have a dose of 75 milligrams (75 mg)?

No, phentermine doesn’t have a dose of 75 mg. The maximum dose of phentermine is 37.5 mg per day.

If you have concerns or questions about your dosage, speak with your doctor or pharmacist.

Is phentermine taken long term?

No, doctors don’t typically prescribe phentermine oral forms as a long-term treatment. Instead, it’s usually recommended for short-term use. To help people lose weight, doctors recommend some strategies along with taking phentermine. These are typically exercise, behavior changes, and a diet low in calories.

If you have questions about how long you should take phentermine oral forms, talk with your doctor.

How phentermine is taken

You’ll swallow phentermine’s tablet or capsule. If you take the orally disintegrating tablet (ODT), you’ll place it on or under your tongue. Doing so will dissolve it. You’ll take any of phentermine’s oral forms one to three times per day with or without food. 

Your doctor may advise that you take this medication around the same time each day. This keeps a consistent amount of the drug in your body. And that can help it work more effectively.  

Usually, doctors will recommend taking phentermine 2 hours after a meal. Avoid taking phentermine in the late evening. If you do, it can cause trouble sleeping.

Phentermine oral tablets have a score line (groove) so you can split them in half, if needed. It’s not known whether it’s safe to chew or crush phentermine oral tablets or capsules. If it’s hard for you to swallow tablets or capsules, view this article. It provides suggestions on how to swallow medications that come in pill form. You can also ask your doctor whether the ODT might be best for you.

If you’re having difficulty taking your medication, be sure to talk with your doctor or pharmacist. They can offer recommendations about taking it.

Pill bottle with text 'Starts at $4'

Free prescription coupons

Seriously … free. Explore prices that beat the competition 70% of the time.

Get free card

Phentermine coupon

Visit this page to access Optum Perks coupons and get price estimates for phentermine when you use the coupons. These coupons can provide significant savings on your prescription costs. 

Note: Optum Perks coupons cannot be used with any insurance copays or benefits.

Overdose of phentermine

It’s important that you do not take more phentermine oral forms than your doctor prescribes. Doing so can lead to serious side effects. 

Symptoms of phentermine overdose

Symptoms of an overdose can include:

What to do if you take too much phentermine

If you think you’ve taken too much phentermine, call your doctor or pharmacist right away. Or you could call 800-222-1222 to speak with someone at America’s Poison Centers. You can also use its online resource. If you have severe symptoms, call 911 or a local emergency number immediately. You can also go to the closest emergency room.

What to ask your doctor

This article describes the usual recommended dosages for phentermine oral forms. If your doctor prescribes this medication, they’ll determine the dosage that’s best for you.

Do not change your dosage of phentermine oral forms without your doctor’s recommendation. You should take phentermine oral forms exactly as your doctor prescribes them. Let your doctor know if you have concerns or questions about your treatment plan.

Here’s a list of some possible questions you may want to ask your doctor:

  • If I’m losing weight with phentermine, when can my dosage be lowered?
  • Does my dosage of phentermine depend on my weight at the start of treatment?
  • How will I know which dose of phentermine is working best for me?

Disclaimer: Optum Perks has made every effort to make certain that all information is factually correct, comprehensive, and up to date. However, this article should not be used as a substitute for the knowledge and expertise of a licensed healthcare professional. You should always consult your doctor or another healthcare professional before taking any medication. The drug information contained herein is subject to change and is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. The absence of warnings or other information for a given drug does not indicate that the drug or drug combination is safe, effective, or appropriate for all patients or all specific uses.

Article resources