Signs of pyloric stenosis usually appear within three to six weeks after birth. Pyloric stenosis is rare in babies older than age 3 months.

Watch for these signs and symptoms:

  • Projectile vomiting. Pyloric stenosis often causes projectile vomiting — the forceful ejection of milk or formula up to several feet away. Vomiting occurs within 30 minutes after your baby eats. Vomiting may be mild at first and gradually become more severe as the pylorus opening narrows. The vomit may sometimes contain blood.
  • Persistent hunger. Babies who have pyloric stenosis often want to eat soon after vomiting.
  • Stomach contractions. You may notice wave-like contractions (peristalsis) that ripple across your baby's upper abdomen soon after feeding but before vomiting. This is caused by stomach muscles trying to force food through the narrowed pylorus.
  • Dehydration. Your baby may cry without tears or become lethargic. You may find yourself changing fewer wet diapers or diapers that aren't as wet as you expect.
  • Changes in bowel movements. Since pyloric stenosis prevents food from reaching the intestines, babies with this condition may be constipated.
  • Weight problems. Pyloric stenosis can keep a baby from gaining weight, and sometimes can cause weight loss.

When to see a doctor

Contact your baby's doctor if your baby is:

  • Frequently vomiting after feeding
  • Projectile vomiting
  • Less active or seems unusually irritable
  • Urinating much less frequently or is having noticeably fewer bowel movements
  • Not gaining weight, or even losing weight
Nov. 16, 2012