What is the recommended Body Mass Index (BMI) for phentermine use?

From the Guidelines

Phentermine is typically recommended for individuals with a Body Mass Index (BMI) of 30 or higher, as indicated by the most recent and highest quality study 1. When considering the use of phentermine, it's essential to evaluate the patient's overall health and potential risks associated with the medication.

• The medication is usually prescribed for a short-term period, typically 3-12 weeks, and should be used in conjunction with diet and exercise for effective weight management.
• Phentermine works by stimulating the central nervous system, which increases heart rate and blood pressure while decreasing appetite.
• It's crucial to note that phentermine is not suitable for everyone, particularly those with cardiovascular disease, hyperthyroidism, glaucoma, history of drug abuse, or women who are pregnant or breastfeeding.
• The medication should only be used under close medical supervision, with regular monitoring of vital signs and potential side effects, as reported in the study 1.
• Weight loss results vary, but patients typically lose 5-10% of their initial body weight when combining phentermine with lifestyle modifications, as seen in the 28-week randomized controlled trial comparing phentermine/topiramate extended-release with phentermine monotherapy and topiramate monotherapy in adults with obesity 1.
• The recommended dosage of phentermine is 15 to 37.5 mg orally once daily in the morning, with low-dose phentermine recently receiving FDA approval under the brand name Lomaira, as a scored 8-mg tablet that can be prescribed up to 3 times per day 1.
• Appropriate candidates for phentermine include patients with obesity who need assistance with appetite suppression, particularly those without evidence of active or unstable coronary disease, or uncontrolled hypertension, as stated in the study 1.

From the FDA Drug Label

Phentermine Hydrochloride is a sympathomimetic amine anorectic indicated as a short-term adjunct (a few weeks) in a regimen of weight reduction based on exercise, behavioral modification and caloric restriction in the management of exogenous obesity for patients with an initial body mass index greater than or equal to 30 kg/m 2, or greater than or equal to 27 kg/m 2 in the presence of other risk factors (e.g., controlled hypertension, diabetes, hyperlipidemia).

The recommended Body Mass Index (BMI) for phentermine use is:

• Greater than or equal to 30 kg/m 2
• Or greater than or equal to 27 kg/m 2 in the presence of other risk factors, such as:
  • Controlled hypertension
  • Diabetes
  • Hyperlipidemia 2

From the Research

Recommended Body Mass Index (BMI) for Phentermine Use

The recommended BMI for phentermine use is typically considered to be 27 kg/m2 or higher, with at least one obesity-related comorbidity, or a BMI of 30 kg/m2 or higher without any comorbidities.

• Studies have shown that phentermine is effective in promoting weight loss in individuals with a BMI of 27-45 kg/m2 3.
• A real-world clinical practice study found that patients with a BMI of 30 kg/m2 or higher, or 27 kg/m2 or higher with at least one obesity-related comorbidity, who were prescribed phentermine, achieved significant weight loss 4.
• Another study found that phentermine was effective in improving anthropometric variables in obese Mexican patients with a BMI of 27 kg/m2 or higher 5.
• A comparison of the efficacy of anti-obesity medications, including phentermine, found that phentermine was associated with a significantly higher prevalence of ≥5% weight loss than other medications, except for liraglutide, in patients with a BMI of 27 kg/m2 or higher 6.
• A systematic review and meta-analysis of phentermine/topiramate therapy found that it resulted in an average weight loss of 7.73 kg in adults with overweight or obesity, with a BMI of 27 kg/m2 or higher 7.

Key Points

• Phentermine is typically recommended for individuals with a BMI of 27 kg/m2 or higher, with at least one obesity-related comorbidity, or a BMI of 30 kg/m2 or higher without any comorbidities.
• Studies have shown that phentermine is effective in promoting weight loss in individuals with a BMI of 27-45 kg/m2.
• Phentermine has been found to be effective in improving anthropometric variables and reducing body weight in obese patients with a BMI of 27 kg/m2 or higher.