Does Phentermine pose a risk of addiction?

From the Guidelines

Phentermine does pose a risk of addiction, but it is considered to be low.

Key Points

• Phentermine is classified as a Schedule IV-controlled substance due to concerns for abuse and dependence 1.
• However, a recent review found that phentermine was not associated with increased risk of major adverse cardiac events compared with usual care, and it has a low risk of dependency or abuse 1.
• The recommended dosage of phentermine is 15–37.5 mg orally once daily, and it should be individualized to achieve adequate response with the lowest effective dose 1.
• Phentermine is an adrenergic agonist, which promotes weight loss by activating the sympathetic nervous system and increasing norepinephrine levels in the central nervous system (CNS) 1.
• Clinicians should avoid prescribing phentermine to patients with a history of substance use disorder, as well as those with certain medical conditions such as coronary artery disease, uncontrolled hypertension, glaucoma, and hyperthyroidism 1.

From the FDA Drug Label

Phentermine is related chemically and pharmacologically to amphetamine (d- and d/l-amphetamine) 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 The least amount feasible should be prescribed or dispensed at one time in order to minimize the possibility of overdosage. Risk of abuse and dependence.

Phentermine poses a risk of addiction due to its chemical and pharmacological relation to amphetamine, a known stimulant with a high potential for abuse. The FDA recommends prescribing the least amount feasible to minimize the possibility of overdosage and acknowledges the risk of abuse and dependence 2.

From the Research

Phentermine Addiction Risk

• The risk of addiction to phentermine is a topic of interest, with several studies investigating its potential for abuse and dependence 3, 4, 5.
• A study published in 2011 found that abrupt cessation of long-term phentermine therapy did not induce amphetamine-like withdrawal, and long-term phentermine therapy did not induce phentermine cravings 3.
• Another study published in 2024 noted that there is no data to support the notion that phentermine is addictive, and recent research suggests that phentermine use is associated with clinically significant weight loss in adults and is generally well tolerated 4.
• A 2014 study investigated the addiction potential of phentermine prescribed during long-term treatment of obesity and found that phentermine abuse or psychological dependence (addiction) does not occur in patients treated with phentermine for obesity 5.
• However, a 2023 study highlighted the potential for drug-drug interactions with phentermine among long-term phentermine consumers, which may result in adverse drug reactions (ADRs) 6.
• A 2013 review noted that phentermine has a declining effect with time and has been recommended for use for only a few weeks due to its potential for addiction, although its pharmacological action is comparable to that of amphetamine, albeit less strong 7.

Key Findings

• Multiple studies have found no evidence of phentermine addiction or dependence 3, 4, 5.
• Phentermine is generally well tolerated and associated with clinically significant weight loss in adults 4.
• Long-term phentermine therapy does not induce phentermine cravings or amphetamine-like withdrawal 3, 5.
• Potential drug-drug interactions with phentermine may result in adverse drug reactions (ADRs) 6.