Symptoms of lactose intolerance usually begin 30 minutes to 2 hours after eating or drinking foods that contain lactose. These signs and symptoms include:
As obvious as the symptoms may seem, lactose intolerance isn’t easily diagnosed by signs and symptoms alone. Many other conditions, including stomach flu and irritable bowel syndrome, can give you similar symptoms.
(Source: The Mayo Clinic, online at www.mayoclinic.com.)