Is Constipation Common with Topiramate?
Constipation is not a common side effect of topiramate, occurring in only 3-10% of patients, making it relatively uncommon compared to other adverse effects like paresthesias, cognitive impairment, and weight loss. 1
Frequency of Constipation
- Constipation occurs in 3-10% of patients taking topiramate, which places it in the lower range of reported adverse effects 1
- In FDA-labeled data from controlled epilepsy trials, constipation occurred in 4% of patients taking topiramate 200 mg/day compared to 0% in placebo 2
- This frequency is substantially lower than the most common side effects such as paresthesias (4-23%), insomnia (5-10%), and cognitive difficulties 1
More Common Side Effects to Anticipate
When prescribing topiramate, you should counsel patients about the following more frequent adverse effects:
- Paresthesias (tingling in arms and legs): 4-23% of patients - this is the most common side effect 1
- Cognitive impairment and difficulty with concentration: occurs frequently, particularly at higher doses 3
- Weight loss and decreased appetite: common and can be significant 1, 2
- Insomnia: 5-10% of patients 1
- Dry mouth: 0-19% of patients 1
Clinical Context for Constipation
- Interestingly, orlistat may be preferred over topiramate in patients with obesity who specifically have constipation as a comorbidity, as orlistat can actually help with constipation due to its gastrointestinal effects 3
- When topiramate is combined with phentermine (as phentermine/topiramate ER), constipation is listed among common side effects but still occurs less frequently than paresthesias, dizziness, and cognitive effects 3
Important Monitoring Considerations
Rather than focusing on constipation, prioritize monitoring for: