Immediate medical care may be needed if a headache, vomiting, fever, or a seizure occurs along with another serious illness. Symptoms of a serious illness include:

• Severe neck stiffness or pain.
• Confusion or extreme irritability.
• Extreme sleepiness.
• Persistent nausea or vomiting.
• Severe sensitivity to light (photophobia).
• Unsteadiness that prevents standing or walking (ataxia or vertigo).
• New double vision, blurred vision, or blind spots.
• Very rapid, difficult breathing.
• Severe pain.
• New and different skin rash or severe bruises.