Can gabapentin (Neurontin) cause syncope?

From the Guidelines

Gabapentin can potentially cause fainting or syncope in some patients, particularly due to its side effects such as dizziness and somnolence, as noted in studies on its use for neuropathic pain management 1. When considering the use of gabapentin, it's crucial to weigh the benefits against the potential risks, including fainting, which could be a result of orthostatic hypotension, central nervous system depression, or drug interactions.

• The mechanism of gabapentin, binding to the α-2-δ subunit of the calcium channel, reducing calcium influx and thus resulting in reduced synaptic neurotransmitter release into the hyperexcited neurone, is key to its efficacy in treating neuropathic pain but also contributes to its side effect profile 1.
• Patients at higher risk for fainting on gabapentin include the elderly, those with pre-existing cardiovascular conditions, and individuals taking multiple medications, especially those that lower blood pressure.
• To mitigate the risk of fainting, it is recommended to start gabapentin at a low dose and gradually increase as tolerated, with careful monitoring of blood pressure and adjustment of other medications as necessary.
• Additionally, advising patients to rise slowly from sitting or lying positions, stay well-hydrated, and avoid alcohol can help minimize the risk of orthostatic hypotension and other adverse effects associated with gabapentin use 1.
• Given the potential for serious adverse reactions, patients experiencing fainting or severe dizziness while on gabapentin should seek immediate medical attention.

From the Research

Gabapentin and Fainting

• Gabapentin is known to cause dizziness, drowsiness, and confusion in some older adults, which may increase the risk of fainting 2.
• A study found that high-dose gabapentin (>600 mg/day) was associated with a higher risk of hospitalization with altered mental status, which may include fainting, compared to low-dose gabapentin (≤600 mg/day) 2.
• Another study reported that gabapentin can cause dizziness (19%), somnolence (14%), and gait disturbance (14%), which may increase the risk of fainting 3.
• A systematic review and meta-analysis found that gabapentinoids, including gabapentin, can cause daytime somnolence, which may increase the risk of fainting 4.
• A comprehensive review of the side effects of gabapentin found that atypical side effects, including myoclonus, ataxia, and respiratory depression, may increase the risk of fainting 5.

Risk Factors for Fainting

• Older adults may be at higher risk of fainting due to gabapentin use, particularly at high doses 2.
• Patients with a history of dizziness, somnolence, or gait disturbance may be at higher risk of fainting while taking gabapentin 3.
• Patients taking high doses of gabapentin (>600 mg/day) may be at higher risk of fainting compared to those taking low doses (≤600 mg/day) 2.

Management of Fainting Risk

• Healthcare practitioners should be aware of the potential risk of fainting associated with gabapentin use and monitor patients closely, particularly older adults and those with a history of dizziness or somnolence 2, 3.
• Patients should be advised to report any symptoms of dizziness, somnolence, or gait disturbance while taking gabapentin, and to seek medical attention if they experience any of these symptoms 3, 4.
• Gabapentin should be used at the lowest effective dose to minimize the risk of fainting and other side effects 2, 3.