Phentermine HCL Tablets

(Commercial Product)

Available Dosage Strengths

37.5 mg

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Product Overview

Description

Phentermine Tablets Description^1-4

Phentermine, a stimulant of the sympathetic central nervous system, is used as an anorectic. It is a schedule IV-controlled substance. The drug closely mimics amphetamine in activity and structure. The drug is also an analog of methamphetamine. Phentermine can be used itself or combined in lower doses with other drugs to enhance its effect. The drug was been approved since 1959 and is used for the following indications:

For the treatment of obesity (short term use in combination with reduced calorie intake and lifestyle modifications) in patients with a body mass index of 30 kg/m2 or patients with a body mass index of 27 kg/m2 with a comorbidity of hypertension, diabetes or dyslpidemia.

Mechanism of Action

Mechanism of Action^1,2

Phentermine predominantly acts in the central nervous system (CNS), within the hypothalamus and limbic systems, where it works on appetite regulation. It stimulates the release of norepinephrine and dopamine from the nerve, and its reuptake is inhibited. The increased norepinephrine may decrease hunger through a reduction in hungry messaging.

Adverse Reactions

Adverse Reactions^1,2

Common

Gastrointestinal-dry mouth, diarrhea, constipation
Central nervous system-insomnia, dizziness, restlessness, nervousness, tremor, headache
Cardiovascular-tachycardia, increased blood pressure

Contraindications & Precautions

Contraindications & Precautions^1,2

Contraindications

Phentermine is contraindicated in patients with:

A known hypersensitivity to phentermine or any of its ingredients
Contraindicated in pregnancy
Cardiovascular disease (coronary artery disease, arrhythmias, stroke, congestive heart failure, uncontrolled hypertension)
Hyperthyroidism
Glaucoma
History of drug abuse
Agitated states or severe anxiety disorders
Who have used monoamine oxidase inhibitors (MAOIs) within the past 14 days

Precautions

Use with caution in patients with diabetes
Use cautiously in people operating machinery or driving a car

Storage

Store tablets at controlled room temperature 59-86°F (15-30°C). Protect from heat, light, and excessive humidity, and store in closed containers.

References

Phentermine Package insert. Revised March 2024. Accessed June 20, 2025. https://www.adipex.com/globalassets/adipex/adipex_pi.pdf
Clinical Pharmacology phentermine clinical monograph 2025 https://www.clinicalkey.com/pharmacology/
Elmaleh-Sachs A, Schwartz JL, Bramante CT, Nicklas JM, Gudzune KA, Jay M. Obesity Management in Adults: A Review. JAMA. 2023 Nov 28;330(20):2000-2015.
Phentermine https://www.ncbi.nlm.nih.gov/books/NBK547916/#Phentermine.OVERVIEW Accessed June 20, 2025.

Disclaimer

This sheet is a summary. It may not cover all possible drug information about this product. Call your doctor for medical advice and/or about side effects. You may report side effects to the FDA at 1-800-FDA-1088. A Wells Pharmacy Network pharmacist will be happy to answer any questions. For consultation, please call 1-800-622-4510.