You can become suddenly lactose intolerant primarily due to a condition called secondary lactose intolerance. This occurs when the small intestine's ability to produce lactase, the enzyme that digests lactose (milk sugar), is reduced or disrupted. Several factors can cause this, including:
- Injury or infection to the small intestine (such as gastroenteritis or intestinal infections)
- Inflammatory bowel diseases like Crohn's disease or ulcerative colitis
- Celiac disease
- Certain medications like chemotherapy or antibiotics
- Surgery or radiation involving the intestines
- Aging, which naturally reduces lactase production over time
- Prolonged avoidance of dairy
Unlike primary lactose intolerance, which develops gradually due to genetics and aging, secondary lactose intolerance can develop suddenly and may be temporary if the underlying condition is treated and the gut heals. Symptoms typically start a short time after consuming lactose-containing foods and include bloating, cramps, gas, diarrhea, and nausea. If experiencing sudden lactose intolerance symptoms, it's important to consider recent illnesses, medications, or changes in digestive health that may have affected the small intestine's enzyme production.
