Symptoms of milk intolerance can be very uncomfortable. Individuals who experience these symptoms should contact their physician to rule out any other medical conditions with similar symptoms (e.g., irritable bowel syndrome).

Symptoms usually begin between 30 minutes and two hours after consuming a food or drink that contains lactose. The severity of the symptoms varies depending on the amount of lactose consumed and the sensitivity of the individual. Common symptoms include:

• Diarrhea
• Gas
• Stomach cramps
• Nausea
• Abdominal bloating or distension (expansion from inner pressure)
• Bad breath

Individuals who have removed milk and other dairy products from their diet often suffer from some form of calcium and vitamin D deficiency. A lack of sufficient calcium increases the risk of developing osteoporosis, which can lead to bone fractures. A lack of vitamin D can cause bone disease and bone fractures. Both calcium and vitamin D can be added to the diet through other types of foods or dietary supplements.