Compare Dulcolax vs. lactulose

Head-to-head comparisons of medication uses, side effects, ratings, and more.

Dulcolax (Bisacodyl)

Over-the-counter

Generlac (lactulose)

Prescription only
Treats constipation.

Dulcolax (Bisacodyl) works fast and the suppositories work even faster to relieve your constipation, as long as you're okay with it "cramping" your style a bit.

3.8/ 5 average rating with 160 reviewsforDulcolax
Relieves constipation and gets rid of ammonia in people with liver problems.

Generlac (lactulose) relieves constipation and high ammonia levels, but it can take up to 48 hours to work.

Upsides
  • Most people said it was worth taking and it wasn't too much of a hassle.
  • Tablets give overnight relief of your constipation.
  • Dulcolax can also be used to treat constipation caused by spinal cord injury.
  • Suppositories give you quick relief without having to drink a large amount of liquid medicine.
  • Generlac (lactulose) is the first-choice treatment for brain conditions caused by high ammonia levels.
  • Can be used if you have severe chronic constipation leading to blockage.
  • Available in generic.
  • Can be taken orally or rectally.
Downsides
  • Dulcolax can cause cramping, stomach upset, feeling faint, and the feeling that you "have to go right now".
  • You have to be comfortable with putting the medicine in your rectum.
  • Suppositories can cause slight rectal burning.
  • Should not be used if you are on a galactose-restricted diet.
  • Does not provide rapid relief of constipation. Talk to your doctor or pharmacist if you need quick relief.
  • Generlac (lactulose) has a very sweet flavor that most people don't like.
Used for
Dosage forms
  • Pill
  • Suppository
  • Liquid
  • Powder
Price
No pricing information available
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Reviews
160 reviews so far
65%
saidit'sworth it
49%
saiditworked well
16%
saidit'sa big hassle

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Side effects
The Dulcolax (Bisacodyl) FDA package insert doesn’t have numbers about how common side effects are.
The Generlac (lactulose) FDA package insert doesn’t have numbers about how common side effects are.
Risks and risk factors
  • Bowel blockage
    • Age 60 or older
    • Malignancy
    • Other condition that causes blockage or narrowing of bowel
    • Taking medications that cause constipation
  • Laxative dependence
    • Age 60 or greater
    • Taking medications that cause constipation
    • People who can't walk or move well (immobility)
  • Risk to fetus
    • Women of childbearing age
See more detailed risks and warnings
  • Mineral imbalances
    • Taking Generlac (lactulose) for more than 6 months
    • Elderly
    • Taking medications that cause mineral imbalance
    • Not exercising regularly
  • Increased blood sugar
    • Diabetes
  • Problems during colonoscopy
See more detailed risks and warnings