In rare instances, overheating may be a sign of another rare but very serious side effect. When this effect develops, muscles get very stiff over one to three days, and you may feel very confused. A high fever develops. If you start to feel these symptoms, get medical help immediately. Go to the emergency room if you cannot reach your doctor.
Some medicines make people more prone to having seizures.
This is especially true for people who have seizure problems and those who are taking certain other medicines. If you have a seizure, get medical help immediately. It may start with a neck spasm that leads to a stiff neck and stiff tongue. The eye muscles may also be involved the eyes may roll up and back. This reaction can be relieved within minutes with another medicine.