My friend has a red watery eye after she threw up? any idea of what can help or why does she have it. she has been sick it started at around 7.

Common: It is common when you throw up to have watery eye. The strain that occurs from vomiting stimulates the lacrimal gland and one tears. Also your friend may have a virus that can also cause watery eye. Ypu should see a doctor to be sure.

Sub conjunctival : Sounds like a sub conjunctival hemorrhage(a bleed under the conjunctiva/ clear skin like layer of the eye) due to the increased blood pressure from the strain of throwing up. Use artificial tears and if vision changes or pain then see an ophthalmologist.