Emergency symptoms may include:

• Severe trouble breathing. You can't talk at all. Young children may have flared nostrils and their belly moves in and out with every breath.
• Pale, gray, or blue-colored skin or lips.
• Severe and constant pain or pressure in the chest.
• Severe and constant dizziness or lightheadedness.
• Acting confused (new or worsening).
• Passing out (losing consciousness) or being very hard to wake up.
• Slurred speech (new or worsening).
• New seizures or seizures that won't stop.
• Sunken eyes, refusing fluids, or not urinating much. (These are signs of dehydration.)