alosetron vs lactulose
PlainMeds reviewed this comparison against our methodology in August 2026. It places FDA and CMS record fields side by side, without recommending either medication.
Side-by-side comparison of alosetron and lactulose. Data from FDA drug databases (Orange Book, NDC Directory, recalls, shortages) covering 20,000+ approved drugs, plus CMS pricing; see our methodology.
Alosetron (Lotronex) is a medicine for women with severe diarrhea-predominant irritable bowel syndrome (IBS). It helps to reduce diarrhea and stomach pain.
Lactulose is a medicine that helps treat and prevent problems with your brain caused by liver disease. It works by reducing the amount of ammonia in your blood.
Alosetron is used to treat severe diarrhea-predominant irritable bowel syndrome (IBS) in women. It is for women whose IBS symptoms have lasted for 6 months or longer. You should have already ruled out other possible causes of your symptoms. This medicine is only for you if other treatments have not worked well enough.
This medicine treats and prevents portal-systemic encephalopathy. This condition can happen when your liver isn't working well. Lactulose helps lower ammonia levels in your blood, which can improve your mental state and brain function.
Alosetron blocks a substance called serotonin in your gut. Serotonin can speed up bowel movements. By blocking serotonin, alosetron slows down your bowel and reduces diarrhea.
Lactulose is a sugar that is not digested in your body. It travels to your colon where it is broken down by bacteria. This process makes the colon more acidic, which helps to draw ammonia from the blood into the colon, where it is then removed from the body through bowel movements.
- • Constipation
- • Abdominal discomfort and pain
- • Nausea
- • Gastrointestinal discomfort and pain
- • Gas
- • Bloating
- • Belching
- • Abdominal discomfort
- • Cramping
- Diarrhoea 10
- Nausea 8
- Abdominal Pain 6
- Death 6
- Constipation 5
- Nausea 2,524
- Constipation 2,497
- Fall 2,241
- Vomiting 2,047
- Fatigue 2,027
Alosetron can cause serious gut problems, like ischemic colitis (reduced blood flow to the bowel) and severe constipation. These problems can lead to hospitalization, surgery, or even death. Stop taking alosetron right away if you get constipated or have symptoms of ischemic colitis, like bloody diarrhea or bad stomach pain. Call your doctor immediately.
If you need a low-galactose diet, you should not take this medicine. Lactulose solution contains galactose.
It is not known if alosetron can harm your unborn baby. Talk to your doctor if you are pregnant or plan to become pregnant. It is also not known if alosetron passes into breast milk. Talk to your doctor about the best way to feed your baby if you take alosetron.
Tell your doctor if you are pregnant or breastfeeding before taking this medicine. It is not known if lactulose can harm your unborn baby. It is also not known if lactulose passes into breast milk.
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How to Read This alosetron vs lactulose Comparison
alosetron is classified in the 5-HT3 Antagonist (IBS-D) drug class, while lactulose sits within the Osmotic Laxative class. Drugs from different classes work through distinct mechanisms, so a head-to-head comparison illustrates trade-offs rather than equivalence. Both drugs are prescription-only, so a licensed provider must authorize use.
Adverse event totals above are pulled from the FDA's Adverse Event Reporting System (FAERS). For these top-ranked reactions alone, alosetron has 35 submissions while lactulose has 11,336. Those figures reflect cumulative reporting volume, not per-patient risk, so older, widely dispensed drugs typically look worse on count alone. No direct interaction between these two drugs is listed in our FDA-derived dataset, though co-prescription still warrants pharmacist review. Serious warnings, pregnancy guidance, and contraindications can differ even when indications overlap.
A table cannot represent individual circumstances. Data here is sourced from FDA Structured Product Labels (SPL) and FAERS, both of which update as manufacturers and clinicians submit new information. This registry does not provide medical, treatment, substitution, or medication-change directions for alosetron or lactulose.
Registry boundary: This comparison displays source-record fields and does not provide individualized medical direction.