Therapy with a number of drugs may be associated with weight gain.


Factors contributing to drug-induced weight gain may include:

(1) increased appetite

(2) decreased exercise and energy expenditure

(3) decrease in basal metabolic rate

(4) fluid retention

(5) enhanced uptake of nutrients


Drugs associated with weight gain include:

(1) antipsychotic drugs (conventional or atypical, especially olanzepine)

(2) antidepressants

(2a) tricyclic

(2c) monoamine oxidase (MAO) inhibitors

(2d) selective seritonin reuptake inhibitors (SSRI)

(2e) mirtazepine

(3) lithium

(4) corticosteroids, especially high dose

(5) oral contraceptives or progestational agents

(6) oral hypoglycemic agents

(6a) glitazones

(6b) sulfonylureas

(7) insulin

(8) anticonvulsants (carbamezepine, gabapentin, phenytoin, valoproic acid)

(9) antihistamines

(10) pizotifen (agent used in the prophylaxis for migraine)

(11) beta-blockers


The weight gain may cause the patient distress, especially if young. This can contribute to poor adherence to the therapeutic regimen.


A person at risk for undesirable weight gain may benefit from:

(1) a concurrent low calorie diet

(2) increased exercise

(3) behavioral modification

(4) use of the lowest effective dose for the shortest period

(5) switch to an alternative medication with lower potential for weight gain


Drugs of abuse may also contribute to weight gain. A large intake of alcohol may be associated with weight gain. Marijuana use may be associated with excessive eating (if the person can find the refrigerator).


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