The nurse is providing discharge instructions to a client who has been prescribed gabapentin 300 mg PO three times a day for postherpetic neuralgia. Which symptom should the nurse tell the client to report to the healthcare provider?

A. Sexual dysfunction: While sexual dysfunction can occur with certain neurologic or antidepressant medications, it is not a commonly associated adverse effect of gabapentin. Reporting it is reasonable, but it is not considered a typical or urgent concern with this drug. B. Photosensitivity: Gabapentin is not generally linked to photosensitivity reactions. Advising the client to protect against sun exposure is important for drugs known to cause this effect, but it is not a significant safety issue for gabapentin use. C. Rapid weight gain: Sudden or significant weight gain may indicate fluid retention or edema, which can be a rare but serious adverse effect of gabapentin. This could signal heart failure or another systemic complication, requiring prompt provider evaluation. D. Gastric irritation: Gabapentin is usually well tolerated by the gastrointestinal tract. Mild stomach upset may occur but can often be managed by taking the medication with food. This is not a high-priority symptom to report unless it is severe or persistent.