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You should also get medical attention if you cannot keep any food or water down, or are nauseous for more than 48 hours.  You should also seek medical attention if you feel weak, have a fever, have stomach pain, or cannot urinate for 8 hours or more. If there is blood in your vomit, bright red or coffee grounds in appearance and if you have a severe headache or a stiff neck or severe abdominal pain, go see a doctor. You should also take your child to a doctor if she hasn’t urinated in 4-6 hours, she has signs of dehydration, and she is experiencing diarrhea. There are several prescription medications that work to reduce nausea. Most begin working within 30 to 60 minutes.  Promethazine hydrochloride is available as a tablet, syrup, injection, or suppository.  Chlorpromazine is only available as a suppository. Prochlorperazine comes as both tablets and suppositories. Trimetho-benzamide hydrochloride is available as a capsule, injection, syrup, or suppository. Metoclopramide hydrochloride comes as a syrup, tablet, or injection. For relief from nausea connected to motion sickness, ask your doctor about scopolamine or Dramamine patches.

Summary:
Get medical attention right away if you throw up three times or more in one day. Take your child to a doctor if her vomiting lasts more than a few hours, or she has a fever. Ask your doctor for an anti-nausea medication.