Does Lactulose Contain Lactose?
Yes, lactulose solutions contain small amounts of lactose as a residual component from the manufacturing process—specifically less than 1.2 grams of lactose per 15 mL dose. 1
Composition Details
According to the FDA drug label, each 15 mL of lactulose solution contains: 1
- 10 grams of lactulose (the active synthetic disaccharide)
- Less than 1.2 grams of lactose (residual from synthesis)
- Less than 1.6 grams of galactose
- 0.1 grams or less of fructose
Clinical Implications
For Diabetic Patients
Lactulose should be used with caution in diabetics because it contains both galactose (less than 1.6 g/15 mL) and lactose (less than 1.2 g/15 mL). 1
For Lactose-Intolerant Patients
The small amount of lactose present in lactulose is generally not clinically significant for most lactose-intolerant individuals: 2
- In populations with high lactose intolerance prevalence, some guidelines have suggested using lactose itself as an alternative to lactulose for hepatic encephalopathy treatment 2
- Research demonstrates that lactulose and lactose may have similar clinical effects in lactose maldigesters 3
- The residual lactose content (less than 1.2 g per dose) is substantially lower than the typical lactose load that triggers symptoms in lactose-intolerant patients
Manufacturing Context
Lactulose is a synthetic disaccharide derived from lactose through isomerization, which explains why small amounts of lactose remain as a residual component in the final pharmaceutical product. 1, 4
Practical Dosing Considerations
When prescribing lactulose, the lactose content becomes relevant primarily in: 1
- Diabetic patients requiring careful carbohydrate monitoring
- Severely lactose-intolerant patients who may need counseling that trace amounts are present
- Standard dosing ranges from 10-20 g (15-30 mL) daily up to 40 g (60 mL) daily for constipation 5
- For hepatic encephalopathy, initial dosing is 25 mL every 1-2 hours until producing 2-3 soft stools daily 2, 6