From the Guidelines
Amitriptyline can cause weight gain, as it is associated with increased appetite and weight gain in many patients, and clinicians should counsel patients on the risk of weight gain and discuss lifestyle modifications to manage this side effect. The weight gain occurs through multiple mechanisms, including increased appetite, carbohydrate cravings, altered metabolism, and fluid retention. Amitriptyline affects neurotransmitters like serotonin, norepinephrine, and histamine, with the antihistamine effect particularly contributing to increased appetite and weight gain 1.
Some key points to consider when prescribing amitriptyline include:
- Monitoring weight regularly
- Considering lifestyle modifications such as regular exercise and dietary adjustments to help manage weight gain
- Discussing the risk of weight gain with patients and exploring alternative medications with lower weight gain potential if necessary
- Avoiding sudden cessation of amitriptyline to prevent withdrawal symptoms
It's also important to note that other medications, such as metformin and topiramate, may be used to counteract the weight gain effects of amitriptyline, with metformin showing a mean difference of -3.27 kg and topiramate showing a mean difference of -3.76 kg in weight gain 1. However, the primary consideration should be the patient's overall health and well-being, and clinicians should prioritize minimizing weight gain and related complications while effectively managing the patient's condition.
From the FDA Drug Label
Other: Alopecia; edema; weight gain or loss; urinary frequency; increased perspiration
- Weight gain is listed as a possible adverse reaction to amitriptyline.
- The FDA drug label for amitriptyline 2 directly supports the answer that amitriptyline can cause weight gain.
From the Research
Amitriptyline and Weight Gain
- Amitriptyline, a tricyclic antidepressant, has been associated with weight gain in some patients, as reported in a study published in the Journal of Affective Disorders 3.
- The study found that patients taking amitriptyline experienced a mean weight increase of 1.3-2.9 lbs/month, leading to an average total weight gain of 3-16 lbs over 6 months of treatment.
- Another study published in Drugs & Aging 4 discussed the pharmacological properties and therapeutic use of amitriptyline in chronic pain states, but did not specifically address weight gain.
Mechanism of Weight Gain
- A study published in Pharmacology, Biochemistry, and Behavior 5 investigated the effects of chronic amitriptyline and desipramine on food intake and body weight in rats, but found no significant increase in food intake or body weight gain.
- However, the study did find that amitriptyline-treated rats showed a potentiation of acute caloric intake after a single systemic injection of the glucoprivic agent 2-deoxy-D-glucose.
Clinical Evidence
- A Cochrane review published in 2015 6 assessed the analgesic efficacy of amitriptyline for relief of chronic neuropathic pain and found that amitriptyline was associated with a significant increase in adverse events, including weight gain.
- Another study published in Current Medical Research and Opinion 7 investigated the biochemical and endocrinological effects of amitriptyline on weight gain, but found no significant weight gain or changes in glucose tolerance curves, fasting or peak insulin levels, or glucose/insulin curves in healthy volunteers.
Summary of Findings
- The evidence suggests that amitriptyline may be associated with weight gain in some patients, particularly those taking low to modest doses for an extended period 3.
- However, the mechanism of weight gain is not fully understood, and further research is needed to determine the exact causes and risk factors associated with amitriptyline-induced weight gain.