Lactose intolerance and milk allergy are two different things. If you're lactose intolerant, you can't process lactose -- the sugar in milk. If you're allergic to milk, you have an immune system reaction to one or more of the proteins in milk. Despite the differences between lactose intolerance and milk allergy with regard to their causes, they can present with some very similar symptoms.
Gas and Bloating
Typically, gas and bloating are associated more with lactose intolerance than with milk allergy. This is because if you're lactose intolerant, the lactose, or milk sugar, from dairy that you consume passes undigested into your lower intestine, explain Drs. Reginald Garrett and Charles Grisham in their book "Biochemistry." There, bacteria that live in your intestine digest the lactose. This process results in the formation of large quantities of gas, which form pockets in the intestine and lead to intestinal distention.
Diarrhea and Cramping
Either milk allergy or lactose intolerance can cause diarrhea and cramping. The Mayo Clinic notes that diarrhea isn't one of the first symptoms of milk allergy that typically presents itself, but often as milk works its way through the intestinal tract, it can irritate the lining of the intestine if you're allergic to the proteins in milk. This irritation leads to water and mucus accumulating in the lower gut, which causes loose stools. Lactose intolerance also causes accumulation of water in the lower gastrointestinal tract, leading to diarrhea.
Hives and Respiratory Symptoms
While lactose intolerance comes with a host of uncomfortable symptoms, none are actually dangerous. Milk allergies, however, can be very severe. If you experience hives, swelling of the throat, or difficulty breathing after drinking milk, it's a sign of milk allergy, notes the Mayo Clinic. Furthermore, symptoms that present in the throat or affect your ability to breathe can be life-threatening -- if you experience such symptoms after using a dairy product, you should see a doctor right away and stop consuming milk until you've been checked for allergies.
References
- "Biochemistry"; Reginald Garrett, Ph.D. and Charles Grisham, Ph.D.; 2007
- MayoClinic.com: Milk Allergy
