Table 4.

Most frequent adverse events and limitations of use of currently available antiobesity drugs.

Drug	Adverse events	Limitations of use and precautions
Phentermine	Dry mouth, constipation, insomnia	Contraindicated in patients with advanced cardiovascular disease, moderate to severe hypertension, hyperthyroidism, glaucoma, and agitate states. Small increases in heart rate and blood pressure may be observed. Mild to moderate abuse potential.
Diethyl prop ion
Phendimetrazine
Benzphetamine
Orlistat	Fecal urgency, fecal incontinence, flatus with discharge, oily spotting	Contraindicated in chronic malabsorption syndrome, and cholestasis. Must take a multivitamin supplement containing fat-soluble vitamins. Rare cases of liver injury.
Lorcaserin	Headache, dizziness, fatigue, nausea, dry mouth, constipation, cough, hypoglycemia in patients with diabetes	Safety of coadministration with antidepressants has not been established. Monitor for symptoms of toxicity related to serotonin excess. Potential for serotonin syndrome, a rare but serious condition. Monitor for signs and symptoms of valvular heart disease.
Liraglutide 3.0 mg	Nausea, vomiting, diarrhea, constipation, dyspepsia, abdominal pain, headache, fatigue, hypoglycemia, increased lipase	Contraindicated in patients with personal or family history of medullary thyroid carcinoma or Multiple Endocrine Neoplasia syndrome type 2. Should not be used with insulin. Do not use with other GLP-1 agonists. Causes thyroid C-cell tumors in rats and mice. Discontinue if pancreatitis is suspected.
Phentermine/Topiramate	Paresthesia, dizziness, insomnia, dysguesia, constipation, dry mouth	Contraindicated in patients with glaucoma, hyperthyroidism, and during and within 2 weeks of taking monoamine oxidase inhibitors.
		Available under a Risk Evaluation and Mitigation Strategy (REMS) that requires negative pregnancy test before treatment and monthly thereafter to reduce the risk of teratogenicity. Small increase in heart rate. Monitor electrolytes to detect metabolic acidosis and elevated creatinine. Monitor closely for depression, anxiety, and memory problems.
Naltrexone/Bupropion	Nausea, vomiting, headache, dizziness, insomnia, dry mouth, diarrhea	Contraindicated in patients with uncontrolled hypertension, chronic opioid use, seizure disorders, anorexia nervosa or bulimia, during withdrawal from alcohol, barbiturates, benzodiazepines, and antiepileptic drugs. Should not use with other bupropion-containing products and during or within 2 weeks of taking monoamine oxidase inhibitors. Monitor for suicidal ideation and behavior. Monitor for increases in heart rate and blood pressure. Rare cases of hepatotoxicity.

All antiobesity drugs are contraindicated in pregnancy.