My Son Just Started on Whole Milk....

I asked my pedi the same question last year because my husband and his family are practically all lactose intolerant. My pedi told me not to worry that typically lactose intolerance doesn't show up until they are older. For my husband he could consume dairy up until 12. Now any slightest lactose gets him really sick. Also, coughing wouldn't be a symptom of intolerance. It is usually intense gas, diarrhea, or vomiting. Good luck with your little one!

My little girl had to stop drinking milk cause she had a reaction. Her poop was like water. And she was getting sick all the time(couldnt really keep anything down). They put her on soy milk and everything got better. It didnt last forever, Shes 5 now and can have milk. Doctor told me that some children arent ready for milk right away.
i hope this helped!

Reactions to milk would include, but not necessarily have all of, these:

vomitting
diarrhea
painful gas
nausea
irritability
rash, hives, eczema, psoriasis

My middle daughter is lactose intolerant, and has all of these symptoms minus the rashes (since rash means allergy, not intolerance). We'll be confirming the diagnosis with a breathalyzer test at the end of the month. If it's not lactose intolerance, it could be a problem with casein.

Coughing could be from phlegm from allergies or a cold, since coughing occurs when there's post-nasal drip or something is stuck that only coughing can dislodge. If the baby has a runny nose due to teething, the coughing could be from that.

If the cough becomes chronic with no clear origin, then you'll have to take him to be checked out, but coughing is NOT a sign of an allergy or of an intolerance to milk.

my daughter reacted badly to whole milk, we had to put her back on formula and gradually mix the formula and whole milk until she was slowly on whole milk

My son did, actually, have a reaction (splotches around his mouth) and he continued to do so until he turned almost 15 months. We had to introduce it slowly (once every few weeks). He had no problems with some cheeses, though. Good luck-and if you think he has a reaction, just go slow.