Several types of over-the-counter medicine can help you poop, and the best choice depends on how quickly you need relief and what’s causing the problem. Stimulant laxatives work fastest (6 to 12 hours), while fiber supplements and osmotic laxatives take 2 to 3 days but are gentler on your body. Here’s how each option works and when to reach for it.
Stimulant Laxatives: The Fastest Option
If you need results soon, stimulant laxatives are the quickest over-the-counter choice. They work by triggering the muscles in your intestines to contract and push stool through. Common brands include Dulcolax (bisacodyl) and Senokot (senna). Most people have a bowel movement within 6 to 12 hours, so taking one before bed often means relief by morning.
Speed comes with trade-offs. Senna-based products irritate the lower intestinal tract, and repeated use can weaken the nerve and muscle signals your colon relies on to move things along on its own. This is sometimes called “lazy bowel.” Stimulant laxatives are best treated as a short-term fix, not a daily habit.
Osmotic Laxatives: Gentle and Widely Used
Osmotic laxatives pull water into the colon, which softens stool and makes it easier to pass. The most popular option is polyethylene glycol 3350, sold as MiraLax. You dissolve about one heaping tablespoon of the powder into 8 ounces of water, juice, coffee, or another beverage and drink it once a day. It typically takes 2 to 4 days to produce a bowel movement, so it’s not an emergency solution.
Milk of Magnesia (magnesium hydroxide) is another osmotic laxative and tends to work a bit faster for some people. It draws water into the intestines the same way but also mildly stimulates gut movement. Magnesium supplements in other forms, like magnesium citrate and magnesium oxide, can also loosen stool. Magnesium citrate is easily absorbed and commonly causes diarrhea at higher doses, while magnesium oxide is poorly absorbed but frequently used for constipation. The upper limit for supplemental magnesium is around 350 mg per day; going higher increases the risk of diarrhea and cramping.
Fiber Supplements: Best for Staying Regular
Bulk-forming laxatives are really just concentrated fiber. They add soluble fiber to your stool, which draws water in and makes stool bigger and softer. The added bulk triggers your colon to contract naturally. Common products include psyllium (Metamucil), methylcellulose (Citrucel), and polycarbophil (FiberCon).
These take the longest to kick in, anywhere from 12 hours to 3 days, and they work best when you take them consistently and drink plenty of water. Of all the options on this list, fiber supplements are the safest for daily, long-term use. They’re also the closest to what your body does on its own when you eat enough fruits, vegetables, and whole grains.
Stool Softeners: When Straining Is the Problem
Stool softeners like docusate sodium (Colace) work differently from laxatives. They increase the amount of water absorbed into your stool so it comes out softer, reducing the need to strain. Docusate also gently stimulates the muscles lining your gut to help move things along.
Stool softeners are a good fit after surgery, during pregnancy, or whenever pushing is painful or risky (such as with hemorrhoids). They’re mild, though, so if your stool is truly stuck or you haven’t gone in several days, a softener alone may not be enough.
Choosing the Right One
Your best match depends on the situation:
- Occasional, mild constipation: Start with a fiber supplement and extra water. Give it 2 to 3 days.
- Moderate constipation that hasn’t responded to fiber: Try an osmotic laxative like MiraLax. Expect results in 2 to 4 days.
- Need relief tonight: A stimulant laxative like bisacodyl or senna will usually work within 6 to 12 hours. Limit use to a few days.
- Hard, dry stool or pain when straining: A stool softener can make passing stool more comfortable.
Constipation During Pregnancy
Constipation is common during pregnancy, and not every laxative is appropriate. The first-line approach is increasing water, dietary fiber, and light physical activity. If that’s not enough, bulk-forming agents like psyllium are a safe next step. Osmotic laxatives, including MiraLax and Milk of Magnesia, are also considered safe in pregnancy because very little is absorbed into the bloodstream. However, using them regularly over a long period can lead to electrolyte imbalances. Probiotics have shown no adverse outcomes for stool regularity during pregnancy either.
Prescription Options for Chronic Constipation
When over-the-counter products don’t solve the problem, prescription medications target constipation through different pathways. These include lubiprostone (Amitiza), linaclotide (Linzess), plecanatide (Trulance), and prucalopride (Motegrity). They work by increasing fluid secretion in the intestines or speeding up gut motility, and they’re typically reserved for people with ongoing constipation that hasn’t responded to standard laxatives.
People taking opioid pain medications face a specific type of constipation because opioids slow the colon’s natural contractions. Separate prescription drugs, including methylnaltrexone (Relistor), naldemedine (Symproic), and naloxegol (Movantik), block the opioid’s effect on the gut without interfering with pain relief.
Risks of Overusing Laxatives
Using any laxative too frequently can backfire. The most common long-term risk is that your colon becomes dependent on the medication and loses its ability to move stool on its own. This weakening of nerve and muscle function is sometimes called lazy bowel, and it creates a cycle where you feel like you need the laxative even more.
Overuse also causes significant water and electrolyte losses. Your body depends on a careful balance of salts like sodium and potassium to regulate muscle contractions, nerve signals, and heart rhythm. Chronic laxative use can deplete those minerals, leading to muscle weakness, numbness, irregular heartbeat, and in extreme cases, seizures or cardiac arrest. Prolonged misuse has also been linked to kidney problems, liver damage, and rectal bleeding.
If you’ve been relying on laxatives for more than a couple of weeks without improvement, or if you notice blood in your stool, unexplained weight loss, persistent abdominal pain, or fever alongside constipation, those are signs something beyond simple constipation may be going on.