Vomiting infant

I have an 8 month-old son who projectile vomits at least 3-4 times a day. I have had him to his Doctor many times now and he just says it is teething and this is normal behaviour.
My son is underweight and I worry about this as well as him dehydrating. I have never seen a teething baby projectile vomit and certainly not multiple times a day, spitting up maybe, but not to this extreme.
He has seen other Doctors in the same office and their opinion is that he has a virus. This has been going on now for 6 months.
What do you think?

I can understand your concerns. If it is projectile vomiting, it suggests he has a high but only partial gut obstruction which is at the bottom of the stomach or in his intestine very soon after. Projectile vomiting is where the vomit comes out like water from a fully turned on hose. It clears the baby’s bib and usually mother’s lap. Copious (and even forceful) vomiting that is not truly projectile suggests gastro-oesophageal reflux (a complex term that I will just call reflux from now on).

Reflux is due to a failure of the valve-like mechanism at the bottom end of the gullet where it enters the stomach. We all suffer reflux from time to time when we can feel fluid coming back up our gullets. Adults just swallow it down again, but babies let it flow out.

I agree this problem is not due to teething. All you get with teething is teeth, misery and excess salivation.

As this has been going on for 6 months, your son should be investigated. The first test should be a barium meal which will show any high gut obstruction and reflux if they are present.

Any high part obstruction will require surgery. Reflux will resolve by itself over the next few months. As he is underweight, a high calorie formula while you are waiting might be warranted. A dietician can help you with this.