How to deal with pyloric stenosis in an 18 year old?

Not pyloric stenosis: I wouldn't think of pyloric stenosis in an 18yo, as it is a condition we see early in infancy. It is extremely uncommon after 6 months of age. Many other conditions can cause vomiting or abnormal emptying of the stomach for a teen-- from stress triggered vomiting, to gastric ulcers to outlet obstruction from other tissues around the stomach. You may want to have the problem more fully evaluated.

Unlikely: It is unlikely that your 18 year-old has pyloric stenosis. Can he/she have vomiting, yes. All vomiting is not pyloric stenosis. At 18 years it could be a stricture at the level of the pylorus secxondary to irritation or ulcer. This should be worked up by gastroenterologist. May need endoscopy and perhaps injection of botox.