What is the best appetite suppressant for a generally healthy adult patient?

Best Appetite Suppressant for Generally Healthy Adults

For generally healthy adults seeking weight loss, phentermine (15-30 mg daily) is the best appetite suppressant, used short-term (a few weeks) as an adjunct to diet, exercise, and behavioral modification in patients with BMI ≥30 kg/m² or ≥27 kg/m² with comorbidities. 1

Primary Recommendation: Phentermine

Phentermine is FDA-approved specifically for appetite suppression in obesity management and should be the first-line pharmacologic choice when lifestyle modifications alone are insufficient. 1

Dosing and Administration

• Standard dose: 15-30 mg taken approximately 2 hours after breakfast 1
• Duration: Short-term use only (a few weeks per FDA labeling) 1
• Timing: Avoid late evening administration due to insomnia risk 1
• Renal impairment: Maximum 15 mg daily if eGFR 15-29 mL/min/1.73 m²; avoid if eGFR <15 mL/min/1.73 m² 1

Patient Selection Criteria

Use phentermine only in patients meeting these criteria: 1

• BMI ≥30 kg/m², OR
• BMI ≥27 kg/m² with obesity-related comorbidities (controlled hypertension, diabetes, hyperlipidemia)
• Age >16 years
• Committed to comprehensive weight reduction program including diet, exercise, and behavioral modification

Critical Contraindications

Absolute contraindications that must be screened before prescribing: 1

• History of cardiovascular disease (coronary artery disease, stroke, arrhythmias, heart failure, uncontrolled hypertension)
• Current or recent (within 14 days) monoamine oxidase inhibitor use
• Hyperthyroidism
• Glaucoma
• Agitated states or history of drug abuse
• Pregnancy or nursing
• Known hypersensitivity to sympathomimetic amines

Alternative Long-Term Options

While phentermine is limited to short-term use, four medications are approved for long-term obesity management (>12 weeks) if sustained pharmacotherapy is needed: 2

Long-Term Appetite Suppressants

• Naltrexone ER/bupropion ER: Combination therapy acting on central appetite pathways 2
• Phentermine/topiramate controlled-release: Extended formulation for chronic use 2
• Liraglutide: GLP-1 receptor agonist that enhances satiety 2, 3
• Orlistat: Decreases fat absorption (not a true appetite suppressant) 2

These agents should be considered when patients require pharmacotherapy beyond the few-week limitation of phentermine monotherapy. 2

Common Pitfalls and Caveats

Do Not Combine Appetite Suppressants

Never combine phentermine with other weight loss drugs, including over-the-counter preparations, herbal products, or serotonergic agents (SSRIs). 1 The safety and efficacy of combination therapy has not been established, and historical combinations (phentermine-fenfluramine) were associated with primary pulmonary hypertension. 1

Monitor for Serious Adverse Effects

Instruct patients to report immediately: 1

• New dyspnea or exercise intolerance (possible primary pulmonary hypertension)
• Angina pectoris
• Syncope
• Lower extremity edema

Sympathomimetic Side Effects

All catecholamine-pathway appetite suppressants (phentermine, diethylpropion, mazindol, phenylpropanolamine) have stimulant and sympathomimetic properties that may cause insomnia, increased heart rate, and elevated blood pressure. 4, 5 The American Diabetes Association specifically warns that some appetite suppressants may increase blood pressure and must be used with care in hypertensive patients. 6

Context-Specific Considerations

Not for Cancer-Related Anorexia

The evidence provided addresses appetite stimulants for cancer cachexia (megestrol acetate, corticosteroids), which is the opposite clinical scenario. 6 These agents increase appetite in disease-related anorexia and are not appropriate for healthy adults seeking weight loss.

Cyproheptadine Is Not Indicated

Cyproheptadine is an appetite stimulant used in specific populations (cystic fibrosis, some pediatric conditions) and has no role in appetite suppression for weight loss. 7, 8

Clinical Algorithm

Follow this stepwise approach:

1. Confirm eligibility: BMI ≥30 or ≥27 with comorbidities, age >16 years 1
2. Screen for contraindications: Cardiovascular disease, MAOI use, hyperthyroidism, glaucoma, pregnancy 1
3. Establish comprehensive program: Diet, exercise, behavioral modification must be in place 1
4. Prescribe phentermine: 15-30 mg daily, 2 hours after breakfast 1
5. Limit duration: Use for a few weeks only per FDA labeling 1
6. Transition to long-term agent if needed: Consider naltrexone/bupropion, phentermine/topiramate ER, or liraglutide for sustained therapy 2
7. Monitor closely: Watch for cardiovascular symptoms, pulmonary hypertension signs 1

Phentermine remains the most established short-term appetite suppressant with the clearest FDA indication for this specific purpose in healthy adults with obesity. 1