Phentermine Hydrochloride

PHENTERMINE HYDROCHLORIDE — phentermine hydrochloride capsule


Phentermine hydrochloride capsules are indicated as a short-term (a few weeks) adjunct 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 ≥ 30 kg/m2 , or ≥ 27 kg/m2 in the presence of other risk factors (e.g., controlled hypertension, diabetes, hyperlipidemia).

Below is a chart of body mass index (BMI) based on various heights and weights.

BMI is calculated by taking the patient’s weight, in kilograms (kg), divided by the patient’s height, in meters (m), squared. Metric conversions are as follows: pounds ÷ 2.2 = kg; inches x 0.0254 = meters.


(click image for full-size original)

The limited usefulness of agents of this class, including phentermine, [see CLINICAL PHARMACOLOGY (12.1, 12.2)] should be measured against possible risk factors inherent in their use such as those described below.


Exogenous Obesity

Dosage should be individualized to obtain an adequate response with the lowest effective dose.

The usual adult dose is 15 mg to 30 mg as prescribed by the physician, at approximately 2 hours after breakfast for appetite control. Administration of one 30 mg capsule daily has been found to be adequate in depression of the appetite for 12 to 14 hours. Phentermine is not recommended for use in pediatric patients ≤16 years of age.

Late evening medication should be avoided because of the possibility of resulting insomnia.


Capsules containing 15 mg or 30 mg phentermine hydrochloride (equivalent to 12 mg or 24 mg phentermine base, respectively).

15 mg capsules: gray opaque cap, yellow opaque body with black imprint “N1” on both the cap and body, filled with powder.

30 mg capsules: blue cap, natural body with black imprint “N16” on both the cap and body, filled with powder.


• History of cardiovascular disease (e.g., coronary artery disease, stroke, arrhythmias, congestive heart failure, uncontrolled hypertension)
• During or within 14 days following the administration of monoamine oxidase inhibitors
• Hyperthyroidism
• Glaucoma
• Agitated states
• History of drug abuse
• Pregnancy [see USE IN SPECIFIC POPULATIONS (8.1)]
• Known hypersensitivity, or idiosyncrasy to the sympathomimetic amines


5.1 Co-administration with Other Drug Products for Weight Loss

Phentermine hydrochloride capsules are indicated only as short-term (a few weeks) monotherapy for the management of exogenous obesity. The safety and efficacy of combination therapy with phentermine and any other drug products for weight loss including prescribed drugs, over-the-counter preparations, and herbal products, or serotonergic agents such as selective serotonin reuptake inhibitors (e.g., fluoxetine, sertraline, fluvoxamine, paroxetine), have not been established. Therefore, co-administration of phentermine and these drug products is not recommended.

5.2 Primary Pulmonary Hypertension

Primary Pulmonary Hypertension (PPH) – a rare, frequently fatal disease of the lungs – has been reported to occur in patients receiving a combination of phentermine with fenfluramine or dexfenfluramine. The possibility of an association between PPH and the use of phentermine alone cannot be ruled out; there have been rare cases of PPH in patients who reportedly have taken phentermine alone. The initial symptom of PPH is usually dyspnea. Other initial symptoms may include angina pectoris, syncope or lower extremity edema. Patients should be advised to report immediately any deterioration in exercise tolerance. Treatment should be discontinued in patients who develop new, unexplained symptoms of dyspnea, angina pectoris, syncope or lower extremity edema, and patients should be evaluated for the possible presence of pulmonary hypertension.

5.3 Valvular Heart Disease

Serious regurgitant cardiac valvular disease, primarily affecting the mitral, aortic and/or tricuspid valves, has been reported in otherwise healthy persons who had taken a combination of phentermine with fenfluramine or dexfenfluramine for weight loss. The possible role of phentermine in the etiology of these valvulopathies has not been established and their course in individuals after the drugs are stopped is not known. The possibility of an association between valvular heart disease and the use of phentermine alone cannot be ruled out; there have been rare cases of valvular heart disease in patients who reportedly have taken phentermine alone.

5.4 Development of Tolerance, Discontinuation in Case of Tolerance

When tolerance to the anorectant effect develops, the recommended dose should not be exceeded in an attempt to increase the effect; rather, the drug should be discontinued.

5.5 Effect on the Ability to Engage in Potentially Hazardous Tasks

Phentermine may impair the ability of the patient to engage in potentially hazardous activities such as operating machinery or driving a motor vehicle; the patient should therefore be cautioned accordingly.

5.6 Risk of Abuse and Dependence

Phentermine is related chemically and pharmacologically to amphetamine (d- and dl lamphetamine) and other related stimulant drugs have been extensively abused. The possibility of abuse of phentermine should be kept in mind when evaluating the desirability of including a drug as part of a weight reduction program. See DRUG ABUSE AND DEPENDENCE (9) and OVERDOSAGE (10).

The least amount feasible should be prescribed or dispensed at one time in order to minimize the possibility of overdosage.

5.7 Usage with Alcohol

Concomitant use of alcohol with phentermine may result in an adverse drug reaction.

5.8 Use in Patients with Hypertension

Use caution in prescribing phentermine for patients with even mild hypertension (risk of increase in blood pressure).

5.9 Use in Patients on Insulin or Oral Hypoglycemic Medications for Diabetes Mellitus

A reduction in insulin or oral hypoglycemic medications in patients with diabetes mellitus may be required.

5.10 Risk of Allergic Reactions due to Tartrazine

Phentermine hydrochloride capsule, 15 mg contains FD&C Yellow No. 5 (tartrazine) which may cause allergic-type reactions (including bronchial asthma) in certain susceptible persons. Although the overall incidence of FD&C Yellow No. 5 (tartrazine) sensitivity in the general populations is low, it is frequently seen in patients who also have aspirin hypersensitivity.


The following adverse reactions are described, or described in greater detail, in other sections:

• Primary pulmonary hypertension [see WARNINGS AND PRECAUTIONS (5.2)]

• Valvular heart disease [see WARNINGS AND PRECAUTIONS (5.3)]

• Effect on the ability to engage in potentially hazardous tasks [see WARNINGS AND PRECAUTIONS (5.5)]

• Withdrawal effects following prolonged high dosage administration [see DRUG ABUSE AND DEPENDENCE (9.3)]. The following adverse reactions to phentermine have been identified:

Primary pulmonary hypertension and/or regurgitant cardiac valvular disease, palpitation, tachycardia, elevation of blood pressure, ischemic events.

Central Nervous System
Overstimulation, restlessness, dizziness, insomnia, euphoria, dysphoria, tremor, headache, psychosis.

Dryness of the mouth, unpleasant taste, diarrhea, constipation, other gastrointestinal disturbances.


Impotence, changes in libido.

Page 1 of 3 1 2 3

All resources are included in as near-original form as possible, meaning that the information from the original provider has been rendered here with only typographical or stylistic modifications and not with any substantive alterations of content, meaning or intent.

This site is provided for educational and informational purposes only, in accordance with our Terms of Use, and is not intended as a substitute for the advice of a medical doctor, nurse, nurse practitioner or other qualified health professional.

Privacy Policy | Copyright © 2020. All Rights Reserved.