The most common side effects of VNS Therapy™ include:

Hoarseness
Shortness of breath
Sore throat
Coughing

These side effects generally only occur during stimulation and usually decrease over time. The most common side effect of the surgical procedure is infection.

Children under 12 may have a greater risk of infection than those 12 years of age and older and may be more likely to experience lead damage due to higher activity levels and the potential to manipulate the lead. Talk to your physician about the best ways to avoid these complications and about warnings, precautions, side effects, and hazards. Ask about risks that you should know about as well as any other issues that might be appropriate to discuss, such as status epilepticus and sudden unexpected death in epilepsy.

You can find more safety information here.