What medications can cause appetite suppression as a side effect, not as their primary intended effect?

From the Guidelines

Many medications can cause appetite suppression as a side effect rather than their primary purpose, including stimulant medications for ADHD, certain antidepressants, anti-seizure medications, antibiotics, chemotherapy drugs, and blood pressure medications. The most recent and highest quality study on this topic is not directly provided, but based on the available evidence, it appears that medications such as phentermine, a sympathomimetic amine, can cause appetite suppression as a side effect by increasing norepinephrine levels in the brain 1. Some key points to consider when evaluating medications that can cause appetite suppression as a side effect include:

• Stimulant medications for ADHD, such as Adderall (amphetamine salts), Ritalin (methylphenidate), and Vyvanse (lisdexamfetamine), can reduce appetite by increasing norepinephrine and dopamine levels in the brain.
• Certain antidepressants, particularly selective serotonin reuptake inhibitors (SSRIs) like fluoxetine (Prozac), sertraline (Zoloft), and escitalopram (Lexapro), may decrease appetite in some patients by affecting serotonin levels.
• Anti-seizure medications such as topiramate (Topamax) and zonisamide (Zonegran) commonly cause appetite reduction.
• Certain antibiotics including metronidazole (Flagyl) and some fluoroquinolones can temporarily reduce appetite by causing gastrointestinal discomfort.
• Chemotherapy drugs almost universally suppress appetite through multiple mechanisms including nausea, taste changes, and direct effects on metabolism.
• Blood pressure medications like beta-blockers (propranolol, metoprolol) may reduce appetite in some patients. It's essential to note that these appetite-suppressing side effects typically resolve when the medication is discontinued, but patients should consult their healthcare provider before stopping any prescribed medication due to appetite concerns, as sudden discontinuation could be dangerous for certain conditions 1.

From the FDA Drug Label

In US placebo–controlled clinical trials for major depressive disorder, 11% of patients treated with Prozac and 2% of patients treated with placebo reported anorexia (decreased appetite). In US placebo–controlled clinical trials for OCD, 17% of patients treated with Prozac and 10% of patients treated with placebo reported anorexia (decreased appetite) In US placebo–controlled clinical trials for bulimia nervosa, 8% of patients treated with Prozac 60 mg and 4% of patients treated with placebo reported anorexia (decreased appetite). Clinical Considerations Monitor breastfeeding infants for adverse reactions, such as agitation, insomnia, anorexia, and reduced weight gain. Misuse and abuse of methylphenidate may cause increased heart rate, respiratory rate, or blood pressure; sweating; dilated pupils; hyperactivity; restlessness; insomnia; decreased appetite; loss of coordination; tremors; flushed skin; vomiting; and/or abdominal pain

Medications that can cause appetite suppression as a side effect include:

• Fluoxetine (Prozac) 2
• Methylphenidate 3

Key points:

• These medications can cause decreased appetite (anorexia) as a side effect, not as their primary intended effect.
• The incidence of anorexia varies depending on the medication, dosage, and population being studied.

From the Research

Medications that Cause Appetite Suppression as a Side Effect

Several medications can cause appetite suppression as a side effect, not as their primary intended effect. These include:

• Stimulant-type medications, such as methylphenidate 4, which are commonly used to treat attention-deficit/hyperactivity disorder (ADHD) and depression
• Selective serotonin reuptake inhibitors (SSRIs), such as fluoxetine, escitalopram, and sertraline 5, 6, which are used to treat depression and other mental health conditions
• Psychostimulants, such as dextroamphetamine and modafinil 4, which are used to treat ADHD, depression, and other conditions

Mechanisms of Appetite Suppression

The mechanisms by which these medications cause appetite suppression are not fully understood, but may involve:

• Increased levels of serotonin (5-HT) in the brain, which can decrease appetite 7
• Activation of 5-HT receptors, which can also decrease appetite 7
• Interference with the hyperphagic action of neuropeptide Y, which can increase appetite 7

Examples of Medications that Cause Appetite Suppression

Some examples of medications that can cause appetite suppression as a side effect include:

• Methylphenidate, which is used to treat ADHD and depression 5, 4
• Fluoxetine, which is used to treat depression and other mental health conditions 7, 5, 6
• Escitalopram, which is used to treat depression and other mental health conditions 5, 6
• Dextroamphetamine, which is used to treat ADHD and depression 4
• Modafinil, which is used to treat ADHD, depression, and other conditions 4