Dulcolax vs Other Laxatives: Which One Works Best for Constipation?

Constipation doesn’t wait for a convenient time. It hits when you’re stuck in a meeting, traveling, or just trying to relax after a long day. If you’ve reached for Dulcolax (bisacodyl) before, you know it works fast-but is it the best choice? And what if it doesn’t work for you, or gives you cramps? There are other options, and not all of them are created equal. Let’s cut through the noise and compare Dulcolax with the most common alternatives, so you know exactly what to reach for next time.

What is Dulcolax (bisacodyl)?

Dulcolax is a brand name for bisacodyl, a stimulant laxative. It doesn’t soften stool or add bulk. Instead, it wakes up your colon. Bisacodyl triggers muscle contractions in the intestines, pushing waste out. Most people feel the effect within 6 to 12 hours after taking a tablet, and sometimes as fast as 15 to 60 minutes with suppositories.

It’s available as tablets, suppositories, and in some countries as a liquid. The standard tablet dose is 5 mg. Suppositories are often used when you need faster action or can’t swallow pills. It’s not a daily fix-it’s meant for occasional use. Long-term use can make your bowels lazy, leading to dependency.

How does bisacodyl compare to other laxatives?

Not all laxatives work the same way. They’re grouped by how they help you go. Here’s how bisacodyl stacks up against the most common alternatives:

1. Polyethylene glycol (PEG) - MiraLAX, Movicol

PEG is an osmotic laxative. It pulls water into the colon, softening stool and making it easier to pass. Unlike bisacodyl, it doesn’t irritate the bowel lining. People often find it gentler. It takes 1 to 3 days to work, so it’s not fast-but it’s reliable for longer-term use under medical supervision.

For chronic constipation, especially in older adults or people with IBS-C, PEG is often the first-line choice recommended by the British Society of Gastroenterology. It’s also safer for daily use than stimulant laxatives like bisacodyl.

2. Lactulose

Lactulose is another osmotic laxative, but it’s a synthetic sugar your body can’t digest. Gut bacteria ferment it, producing acids and gases that draw water into the colon. It usually takes 24 to 48 hours to work.

It’s commonly used in the UK for constipation in pregnancy and in elderly patients. Some people report bloating and gas with lactulose, which can be worse than with PEG. But it’s less likely to cause cramping than bisacodyl.

3. Senna - Senokot, Ex-Lax

Senna is also a stimulant laxative, like bisacodyl. It works by the same mechanism: irritating the colon lining to trigger contractions. Many people use senna because it’s cheaper and available over the counter without a brand name.

But here’s the catch: senna often causes more cramping than bisacodyl. Studies show that people taking senna report higher rates of abdominal pain and discomfort. Both can lead to dependency if used daily for more than a week. But bisacodyl tends to act faster and with slightly less irritation in some users.

4. Stool softeners - Docusate sodium (Colace)

Docusate sodium doesn’t make you poop. It makes your stool softer by letting water and fat mix into it. It’s great if you’re recovering from surgery, childbirth, or hemorrhoids and need to avoid straining. But it won’t help if your colon is just slow.

It takes 1 to 3 days to work. If you’re constipated and your stool is hard, docusate might help-but if you haven’t had a bowel movement in days, it probably won’t be enough on its own.

5. Magnesium hydroxide - Milk of Magnesia

This is an osmotic laxative that pulls water into the bowel and also has a mild stimulant effect. It usually works in 30 minutes to 6 hours. People like it because it’s fast and cheap.

But it can cause diarrhea if you take too much. It’s not ideal for people with kidney problems because magnesium builds up in the blood if your kidneys aren’t working well. If you’re on other meds, check with a pharmacist-magnesium can interfere with antibiotics and thyroid drugs.

When to choose Dulcolax (bisacodyl)

Dulcolax shines in three situations:

1. You need a fast, predictable result-like before a medical procedure or travel.
2. You’ve tried softer options (like PEG or docusate) and they didn’t work.
3. You can’t tolerate the bloating from lactulose or the cramps from senna.

It’s the go-to for people who want control over timing. The suppository form is especially useful if you’re in pain or can’t swallow pills.

When to avoid bisacodyl

Dulcolax isn’t for everyone. Skip it if:

• You have abdominal pain, nausea, or vomiting-you could have a bowel obstruction.
• You’re pregnant or breastfeeding without checking with your doctor.
• You’ve been constipated for more than two weeks.
• You’ve used stimulant laxatives daily for more than a week.
• You have Crohn’s disease, ulcerative colitis, or a history of bowel surgery.

Using bisacodyl too often can lead to electrolyte imbalances, especially low potassium. That can cause muscle weakness or irregular heartbeat. It’s not dangerous in the short term, but it’s not harmless either.

Real-world advice from the UK

In NHS clinics and GP practices across England and Wales, the standard advice is clear: start with lifestyle changes. Drink more water, eat more fiber (whole grains, beans, vegetables), and move more. If that doesn’t help, try an osmotic laxative like PEG or lactulose first.

Stimulant laxatives like bisacodyl are reserved for when those don’t work-or when you need a quick fix. Pharmacists in Bristol, Manchester, or Edinburgh will often recommend PEG over Dulcolax for regular use because it’s gentler and safer long-term.

If you’re using Dulcolax more than twice a week, talk to your GP. There might be an underlying issue-like hypothyroidism, diabetes, or medication side effects-that’s causing the constipation.

What about natural options?

Prunes, figs, chia seeds, and flaxseed are often suggested as natural laxatives. They work because they’re high in fiber and some contain sorbitol, a natural osmotic agent. But they’re slow. You’d need to eat a lot-like 3-4 prunes daily-to match the effect of one tablet of PEG.

They’re great as a daily support, not as a rescue. Don’t rely on them if you’re in pain or need results within hours.

Final comparison table

What to do if Dulcolax doesn’t work

If you take a Dulcolax tablet and nothing happens after 24 hours, don’t take another. You might have a blockage, or your body just doesn’t respond to stimulants. Try a PEG laxative instead. If that doesn’t work after two days, see your GP.

Also, don’t combine laxatives unless your doctor says so. Mixing bisacodyl with magnesium or senna increases the risk of dehydration and electrolyte loss.

When to see a doctor

Constipation isn’t always just a bowel issue. See a doctor if you have:

• Constipation lasting more than two weeks
• Blood in stool
• Unexplained weight loss
• Severe abdominal pain
• Change in bowel habits (especially if over 50)
• Need to use laxatives more than twice a week

These could signal something more serious-like colon cancer, thyroid problems, or nerve damage. Don’t ignore them.

Next steps if you’re struggling with constipation

Start simple: drink more water-aim for 6 to 8 glasses a day. Add one extra serving of vegetables or whole grains to each meal. Walk for 20 minutes after dinner. These small changes often fix constipation without any pills.

If that doesn’t help, try PEG for 3-5 days. If you still don’t go, then consider Dulcolax as a short-term option. But don’t keep going back to it. Talk to your pharmacist or GP. There’s almost always a better, safer way to manage your bowels long-term.