Varenicline Side Effects and Precautions

Common Side Effects

Nausea occurs in 30-40% of varenicline users, typically mild to moderate, and diminishes over time 1
Insomnia affects 14-15% of users 2
Abnormal or vivid dreams occur in 10-13% of users 2

The National Comprehensive Cancer Network recommends monitoring for neuropsychiatric symptoms, including depression and suicidal ideation/behavior, in patients taking varenicline 3, 1
A large randomized controlled trial (EAGLES trial) found no significant increase in neuropsychiatric adverse events with varenicline compared to nicotine patches or placebo 1, 2
Seizures are a rare but significant risk, especially in patients with brain metastases 3, 2
Cardiovascular events may be slightly increased with varenicline use, according to the European Heart Journal 4

Brain metastases are a contraindication for varenicline due to seizure risk, as recommended by the National Comprehensive Cancer Network 3, 1
Patients should be monitored for development or worsening of neuropsychiatric symptoms, especially those with a history of psychiatric illness, and healthcare providers should weigh the benefits of smoking cessation against the potential risks of neuropsychiatric side effects 3, 1
Nausea may need to be managed carefully in patients with cancer, especially during chemotherapy, and dose adjustments may be considered if clinically indicated to manage side effects 3
Despite these side effects, guidelines indicate that in most circumstances, the side effects related to smoking cessation medications are minimal and are considered an acceptable risk compared to continued smoking, with serious side effects being extremely rare 1

Patients with brain metastases who have a history or elevated risk of seizures should avoid varenicline due to rare but significant seizure risk 5
Careful monitoring is recommended for patients with psychiatric disorders, though recent evidence suggests varenicline does not significantly increase neuropsychiatric adverse events compared to nicotine patches or placebo 6

Despite previous concerns, recent systematic reviews and meta-analyses have not identified a significant link between varenicline and increased risk of serious cardiovascular adverse events 5, 6, 7
The National Comprehensive Cancer Network considers varenicline to have a favorable risk/benefit ratio for patients with cancer who smoke 5, 6, 7