Gabapentin

The most common side effect. Dose-dependent. Often prominent early and may improve with continued use. Can be therapeutic in insomnia but problematic during the day. Contributes to fall risk in elderly patients.

Common, often dose-related. Related to CNS depression. Usually improves with slow titration.

CNS depressant effect on cerebellar and motor coordination. Increases fall risk. Start low and titrate slowly in older patients.

Can occur in the lower extremities. Mechanism unclear. May be mistaken for cardiac or venous insufficiency. More common at higher doses and in older patients.

Mild to moderate. Less than olanzapine or mirtazapine, but present. Some patients gain noticeably over long-term use.

Some patients report difficulty concentrating, word-finding problems, or feeling "foggy." More common at higher doses.

Gabapentin alone rarely causes respiratory depression. In combination with opioids or other CNS depressants, the risk is real and is the basis of the 2019 FDA Drug Safety Communication. This is the most important safety concern in current gabapentin prescribing.

Euphoria at high doses, particularly in patients with substance use disorders. Multiple states have added gabapentin to prescription drug monitoring programs. Screen for substance use history.

Symptoms include anxiety, insomnia, nausea, sweating, and in seizure-prone patients, seizures. Taper over at least 1 week, longer if the patient has been on high doses or prolonged treatment.