You’re standing in the pharmacy aisle staring at dozens of laxative boxes—and you have no idea which one will actually work. You’re not alone. Millions of Americans face this exact situation every year, searching for the best OTC laxatives for constipation to get reliable relief.
Constipation is one of the most common health problems in the United States. Chronic idiopathic constipation (CIC) alone affects roughly 8–12% of the US population. Most people quietly reach for an over-the-counter solution before ever seeing a doctor—yet many end up choosing products with weak or no clinical evidence behind them.
This guide cuts through the confusion. To help you find the best OTC laxatives for constipation, we reviewed the three most authoritative sources available today:
-
Rao & Brenner (2021): A landmark systematic review published in the American Journal of Gastroenterology that screened 1,297 studies and analyzed 41 qualifying RCTs conducted between 2004–2020.
-
AGA–ACG Clinical Practice Guideline (2023): The most up-to-date joint guideline from America’s two leading gastroenterology societies, using the gold-standard GRADE methodology.
-
Mayo Clinic: For patient-friendly safety guidance and laxative categories.
By the end of this article, you will know exactly which products have the strongest evidence, which ones to avoid, and how to choose the right option for your specific situation.
⚡ Quick Answer: Best OTC Laxatives Ranked by Evidence
- MiraLAX (PEG) — Strongest overall; Grade A; first-line for chronic constipation
- Senokot (Senna) — Grade A; fast-acting; short-term use only
- Dulcolax (Bisacodyl) — Grade B; strong 2023 recommendation for rescue use
- Metamucil (Psyllium) — Grade B; best for daily long-term fiber support
- Magnesium-based — Grade B; gentle and effective for occasional use
- Kiwi & Prunes — Grade B; best natural food-based options
- Colace (Docusate) — Grade I; insufficient evidence; not recommended
What Is Constipation? Simple Signs to Watch For
According to Mayo Clinic, constipation means you are having fewer bowel movements than usual, or your stools are hard, dry, and difficult to pass.3 Most doctors define constipation as fewer than three bowel movements per week.
Common symptoms include:
- Straining to pass stool
- Hard or lumpy stools
- Feeling like your bowel never completely empties
- Bloating and abdominal discomfort
Common causes include low fiber intake, not drinking enough water, physical inactivity, certain medications, and aging. Women experience constipation more often than men, and it becomes more common after age 60.
Before reaching for a laxative, Mayo Clinic recommends trying these lifestyle changes first: eat 25–31 grams of fiber daily, drink 8–10 glasses of water per day, and exercise regularly.3 For more on how dehydration causes constipation, see our guide: Does Dehydration Cause Constipation?
How Do We Know Which Laxatives Work? Understanding the Evidence
Not all laxative claims are equal. The 2021 Rao & Brenner review graded each OTC treatment using a clear system:
| Grade | What It Means | Plain English |
|---|---|---|
| Grade A | Good evidence from multiple well-designed trials | âś… Strongly recommended |
| Grade B | Moderate evidence; fewer or smaller trials | âś… Recommended |
| Grade C | Poor evidence from weak trials | ⚠️ Not routinely recommended |
| Grade I | Not enough data to make any recommendation | ❌ Insufficient evidence |
The 2023 AGA–ACG Guideline used the GRADE system with two recommendation strengths:
- Strong recommendation — Most patients should use this. Benefits clearly outweigh risks.
- Conditional recommendation — Good option for many, but decide with your doctor based on your personal situation.
Best OTC Laxatives at a Glance: Full Comparison Table
| Product | Type | 2021 Grade | 2023 AGA–ACG | Onset | Best For | Buy |
|---|---|---|---|---|---|---|
| MiraLAX (PEG) | Osmotic | Grade A ✅ | Strong, Moderate certainty | 24–72 hrs | Chronic constipation | Check Price |
| Senokot (Senna) | Stimulant | Grade A ✅ | Conditional, Low certainty | 6–12 hrs | Short-term relief | Check Price |
| Dulcolax (Bisacodyl) | Stimulant | Grade B ✅ | Strong, Moderate certainty (short-term) | 6–12 hrs | Rescue/occasional | Check Price |
| Metamucil (Psyllium) | Fiber/Bulk | Grade B ✅ | Conditional, Low certainty | 12–72 hrs | Daily prevention | Check Price |
| Milk of Magnesia | Osmotic/Magnesium | Grade B ✅ | Conditional, Very low certainty (MgO) | 6–12 hrs | Gentle overnight | Check Price |
| Magnesium Citrate | Saline/Osmotic | Grade B ✅ | Not separately graded | 30 min–6 hrs | Fast occasional relief | Check Price |
| Colace (Docusate) | Stool Softener | Grade I ❌ | No recommendation issued | 12–72 hrs | Not recommended for constipation | — |
1. MiraLAX (Polyethylene Glycol) — Best Overall OTC Laxative
What Is It and How Does It Work?
MiraLAX contains polyethylene glycol 3350 (PEG), an osmotic laxative. It works by drawing water into the colon, softening stool and making it easier to pass. According to Mayo Clinic, osmotics “draw water into the colon to allow easier passage of stool.”3 PEG is not absorbed by the body, so it stays in the gut and works locally.
What Does the Research Say?
PEG is the most thoroughly studied OTC laxative available. In the 2021 systematic review, PEG received a Grade A recommendation — the highest possible rating — based on 9 clinical trials.1 It is the only OTC laxative supported by both short-term and long-term study data.
The 2023 AGA–ACG Guideline confirmed this with a strong recommendation with moderate certainty of evidence — making PEG the only OTC constipation treatment to receive a strong GRADE recommendation for chronic daily use.2
Pros and Cons
| ✅ Pros • Highest evidence grade (Grade A) • Only OTC laxative with long-term RCT data • Safe for daily chronic use • No dependency or tolerance • Tasteless; easy to mix in any drink |
❌ Cons • Slow onset (24–72 hours) • Not for urgent or immediate relief • May cause bloating or loose stools at high doses |
Who Should Use It?
PEG is the best choice for people with chronic constipation — meaning ongoing, recurring difficulty with bowel movements. It is also safe for elderly adults, pregnant women (under physician guidance), and people who need daily long-term relief without dependency risk. See our full guide on constipation relief for elderly adults.
Onset: 24–72 hours | Use: Daily long-term | → Check Price on Amazon
2. Senokot (Senna) — Best Fast-Acting Natural Laxative
What Is It and How Does It Work?
Senna is a plant-based stimulant laxative made from the leaves and pods of Senna alexandrina. According to Mayo Clinic, stimulants “trigger rhythmic contractions of intestinal muscles to eliminate stool.”3 This speeds up how quickly stool moves through your colon.
What Does the Research Say?
In the 2021 systematic review, senna received a Grade A recommendation, based on two clinical trials showing improved bowel movement frequency versus placebo.1 However, one of those trials used higher doses than are standard in practice — an important limitation.
The 2023 AGA–ACG Guideline gave senna a conditional recommendation with low certainty of evidence — weaker than both PEG and bisacodyl under the GRADE system.2 The guideline notes that while longer-term use is probably fine, more data is needed on tolerance and side effects.
Pros and Cons
| ✅ Pros • Grade A evidence in 2021 review • Fast relief — works in 6–12 hours • Natural plant-based origin • Affordable and widely available |
❌ Cons • Conditional (not strong) 2023 recommendation • Key trial used above-standard doses • Not for daily long-term use • May cause cramping, urgency, diarrhea • Urine may discolor (harmless) |
Onset: 6–12 hours | Use: Short-term/occasional | → Check Price on Amazon
3. Dulcolax (Bisacodyl) — Best for Rescue Relief
What Is It and How Does It Work?
Bisacodyl is a stimulant laxative that activates the muscles lining your intestines, triggering contractions and pushing stool through. According to Mayo Clinic, rectal suppositories of bisacodyl “trigger rhythmic contractions of intestinal muscles and soften stool.”3 It is available in tablet and suppository form.
What Does the Research Say?
Bisacodyl and its close relative sodium picosulfate both received Grade B recommendations in the 2021 review.1 This was a significant upgrade — in the 2005 Ramkumar & Rao review, both had only Grade C recommendations.
The 2023 AGA–ACG Guideline issued a strong recommendation with moderate certainty of evidence for bisacodyl or sodium picosulfate for short-term use (up to 4 weeks) or as rescue therapy.2 This is notably stronger than the conditional recommendation given to senna under the same framework.
Pros and Cons
| ✅ Pros • Strong 2023 AGA–ACG recommendation for short-term use • Grade upgraded from C (2005) to B (2021) • Fast onset (6–12 hrs oral; 15–30 min suppository) • Available in tablets, liquid, and suppositories |
❌ Cons • Strong recommendation is for short-term/rescue only • High rate of cramping and diarrhea at initial doses • Not for daily long-term use |
Onset: 6–12 hours (oral) | Use: Rescue/occasional | → Check Price on Amazon
4. Metamucil (Psyllium Husk) — Best for Daily Fiber Support
What Is It and How Does It Work?
Metamucil contains psyllium husk, a soluble fiber from the seeds of Plantago ovata. According to Mayo Clinic, bulk-forming laxatives like Metamucil “absorb water to form soft, bulky stool, prompting normal contraction of intestinal muscles.”3 It is the gentlest laxative type and the only one that closely mimics natural bowel function.
What Does the Research Say?
Psyllium received a Grade B recommendation in the 2021 systematic review.1 However, it is important to be honest: two placebo-controlled trials found psyllium was no better than placebo for improving overall constipation scores. It was also found to be less effective than lactulose, mangos, and prunes in direct comparisons.
Despite this, psyllium earned a Grade B because it improves stool bulk and consistency, has an excellent safety record, and offers significant additional health benefits beyond constipation alone. The 2023 AGA–ACG Guideline recommends psyllium as a conditional first-line therapy, especially for people with low dietary fiber intake.2 Mayo Clinic calls fiber supplements “the gentlest on your body.”3
For a complete comparison of all fiber supplement options, see our guide:Â 7 Natural Fiber Supplements for Chronic Constipation.
Pros and Cons
| ✅ Pros • Safe for daily long-term use • Also lowers cholesterol and blood sugar • Gentle; suitable for pregnancy and elderly • Supports gut microbiome health • No dependency risk |
❌ Cons • Grade B (moderate, not strong evidence) • Slower than PEG or stimulants • No benefit over placebo in 2 trials • Less effective than mangos, prunes in comparisons • Must be taken with lots of water |
Onset: 12–72 hours | Use: Daily long-term | → Check Price on Amazon
5. Magnesium-Based Laxatives — Best for Gentle Overnight Relief
What Are They and How Do They Work?
Magnesium laxatives work by drawing water into the colon osmotically. Mayo Clinic lists both Milk of Magnesia (magnesium hydroxide) and PEG in the same “oral osmotics” category.3 There are three common forms:
- Magnesium oxide — tablet form; studied in clinical trials
- Magnesium citrate — liquid form; fastest onset (30 min–6 hours)
- Magnesium hydroxide (Milk of Magnesia) — liquid suspension; classic gentle option
What Does the Research Say?
Magnesium salts as a group received a Grade B recommendation in the 2021 review.1 Magnesium oxide specifically was shown to outperform placebo and be non-inferior to senna in one qualifying trial. The 2023 AGA–ACG Guideline gave magnesium oxide a conditional recommendation with very low certainty of evidence — the lowest certainty among all evaluated agents — noting that while results are positive, the evidence base is thin.2
For detailed comparisons of specific magnesium products, see our guide:Â 5 Best Magnesium Supplements for Constipation.
Pros and Cons
| ✅ Pros • Grade B evidence for magnesium salts collectively • Magnesium citrate: very fast onset (30 min–6 hrs) • Non-stimulant; gentle on the gut • Multiple forms available |
❌ Cons • Magnesium oxide: very low certainty in 2023 guideline • Unsafe in kidney disease • Risk of diarrhea or electrolyte imbalance if overused • Efficacy varies between forms |
Onset: 6–12 hours | → Check Price on Amazon📦 Magnesium Citrate: Magnesium Citrate Liquid — Fastest-acting magnesium option.
Onset: 30 min–6 hours | → Check Price on Amazon
6. Kiwi and Prunes — Best Natural Food-Based Options
What Does the Research Say?
Research has found that certain fruits act as effective natural laxatives. The 2021 systematic review gave Grade B recommendations to four fruit-based laxatives: kiwi, prunes (dried plums), mango, and figs.1 These contain fiber, sorbitol, and natural sugars that help retain water in the colon and stimulate bowel movements.
Within the Grade B category:
- Kiwi — supported by two clinical trials; strongest evidence within this group
- Prunes — supported by one clinical trial; in a direct comparison study, prunes outperformed psyllium for stool frequency
- Mango and figs — each supported by single studies; Grade B
Notably, the 2021 review found that psyllium was less effective than mangos and prunes in direct comparisons — meaning these natural options can genuinely outperform a commonly recommended supplement.1
How Much to Use?
- Kiwi:Â 2 fruits per day (as used in trials)
- Prunes: 50–100g per day (about 5–10 prunes)
Pros and Cons
| ✅ Pros • All Grade B; natural and food-based • Prunes outperformed psyllium in direct comparison • Provide vitamins, minerals, antioxidants • No dependency risk; minimal side effects |
❌ Cons • Kiwi allergy exists (rare but possible) • Prunes may cause excessive gas in some people • Less standardized than medications |
For more on fiber-rich foods that help with constipation, see our guide:Â Best Fiber Foods and Fiber Therapy for Gut Health.
7. Docusate (Colace) — Widely Used But Not Supported by Evidence
Docusate sodium (sold as Colace and Dulcolax Stool Softener) is one of the most frequently recommended stool softeners in the US. According to Mayo Clinic, stool softeners “add moisture to stool to soften it, allowing strain-free bowel movements.”3
However, the clinical evidence does not support this mechanism producing real benefit:
- Mayo Clinic states:Â “in controlled clinical trials, there is no evidence that they improve symptoms.”3
- The 2021 Rao & Brenner review found no qualifying post-2004 RCTs for docusate and concluded it has insufficient evidence (Grade I) — meaning there is simply not enough data to recommend it.1
- The 2023 AGA–ACG Guideline evaluated docusate and issued no recommendation, consistent with this finding.2
Docusate has a good safety profile and may still be used in post-surgical settings or to prevent straining where any gentle intervention is preferred. But if you want proven constipation relief, switch to PEG, psyllium, bisacodyl, or senna — all with substantially stronger evidence.
8. Inulin, Polydextrose, and FOS — Not Recommended for Constipation
Despite being widely marketed as gut health supplements, the 2021 systematic review found insufficient evidence (Grade I) for polydextrose, inulin, and fructo-oligosaccharide (FOS) specifically for constipation relief.1 These may benefit gut microbiome health, but should not be relied upon to treat constipation.
Safety: What You Need to Know Before Using Any OTC Laxative
Across all 41 trials included in the 2021 review, no serious adverse events were reported for any OTC laxative.1 Common side effects — bloating, cramping, gas, loose stools — are mild and dose-dependent. However, Mayo Clinic warns that overuse of laxatives can lead to serious health problems, including electrolyte imbalances that affect the heart, muscles, and brain.3
Key safety rules:
- Stimulant laxatives (senna, bisacodyl):Â Effective short-term; do not use daily long-term without a doctor’s guidance
- Magnesium laxatives:Â Avoid if you have kidney disease
- All laxatives: Always drink plenty of water — dehydration can make constipation worse. See: Does Dehydration Cause Constipation?
- Elderly adults: More prone to side effects and drug interactions — see Immediate Constipation Relief for Elderly at Home
- Hemorrhoid patients: Prefer PEG or psyllium to avoid straining — see Natural Ways to Relieve Hemorrhoids and Constipation
How to Choose the Right OTC Laxative for Your Situation
| Your Situation | Best Choice | Why |
|---|---|---|
| Chronic constipation (ongoing) | PEG (MiraLAX) | Strongest evidence; safe daily long-term |
| Need relief tonight | Senna or Bisacodyl | Works in 6–12 hours; use occasionally |
| Need relief in 1–2 hours | Magnesium Citrate | Fastest non-stimulant option; use occasionally |
| Daily gentle maintenance | Psyllium (Metamucil) | Gentle, safe, long-term; bonus health benefits |
| Natural food-first preference | Kiwi + Prunes daily | Grade B; prunes beat psyllium in direct comparison |
| Elderly adult | PEG or Psyllium | Gentlest options; avoid stimulants if possible |
| Have hemorrhoids | PEG or Psyllium | Soften stool without stimulating straining |
For yoga poses that naturally support gut motility, see our guide:Â Yoga for Constipation Relief: 7 Science-Backed Poses.
When to Stop Using OTC Laxatives and See a Doctor
Mayo Clinic says to call your healthcare team immediately if you experience any of the following:3
- Severe stomach cramps or pain
- Unexplained changes in bowel patterns
- Severe diarrhea
- Blood in your stool or rectal bleeding
- Constipation lasting more than 7 days even with laxative use
- Weakness, unusual tiredness, or dizziness
These symptoms may indicate a more serious underlying condition that requires medical evaluation — not just a stronger laxative.
Frequently Asked Questions About OTC Laxatives
What is the number one recommended OTC laxative?
PEG (MiraLAX) is the top-recommended OTC laxative based on clinical evidence. It received a Grade A recommendation in the 2021 Rao & Brenner systematic review and a strong recommendation in the 2023 AGA–ACG Clinical Practice Guideline — the only OTC laxative to achieve both.12
How long does it take for OTC laxatives to work?
- Magnesium citrate:Â 30 minutes to 6 hours (fastest)
- Senna and bisacodyl: 6–12 hours
- Milk of Magnesia: 6–12 hours
- PEG (MiraLAX): 24–72 hours
- Psyllium (Metamucil): 12–72 hours
Is Colace (docusate) effective for constipation?
No. Mayo Clinic states there is “no evidence that they improve symptoms” in controlled clinical trials.3 The 2021 systematic review found insufficient evidence (Grade I), and the 2023 AGA–ACG Guideline issued no recommendation for it. Choose PEG, psyllium, bisacodyl, or senna instead.
Can I use laxatives every day?
It depends on the type. PEG and psyllium are safe for daily long-term use. Stimulant laxatives (senna, bisacodyl) should not be used daily without a doctor’s guidance. Overuse of any laxative can lead to dependency and electrolyte imbalances, as Mayo Clinic warns.3
What is the best natural laxative for constipation?
Among natural foods, kiwi and prunes have the strongest evidence — both receiving Grade B recommendations in the 2021 review. In a direct comparison study, prunes outperformed psyllium for stool frequency. Kiwi is supported by two clinical trials within this group. For natural home remedies, also see: Fast Constipation Relief at Home: 12 Natural Ways.
Is it safe to use laxatives during pregnancy?
Psyllium and PEG are generally considered the safest OTC options during pregnancy, but always consult your doctor first. Stimulant laxatives should be avoided unless prescribed. For pregnancy-related fiber guidance, see our article on high-fiber foods for pregnancy constipation.
Final Verdict: Best OTC Laxatives Ranked by Evidence
After reviewing the 2021 Rao & Brenner systematic review, the 2023 AGA–ACG Clinical Practice Guideline, and Mayo Clinic guidance, here is the complete evidence-based ranking:
| # | Laxative | 2021 Grade | 2023 AGA–ACG | Verdict |
|---|---|---|---|---|
| 1 | PEG (MiraLAX) | Grade A | Strong, Moderate certainty | 🏆 Best overall; first-line for chronic constipation |
| 2 | Bisacodyl / Sodium Picosulfate | Grade B | Strong, Moderate certainty (short-term) | âś… Best rescue/short-term stimulant; upgraded from Grade C |
| 3 | Senna | Grade A | Conditional, Low certainty | âś… Fast-acting; short-term only; one trial used above-standard dose |
| 4 | Magnesium salts | Grade B | Conditional, Very low certainty (MgO) | âś… Gentle; avoid in kidney disease |
| 5 | Psyllium (Metamucil) | Grade B | Conditional, Low certainty | âś… Best for daily prevention; safest long-term fiber |
| 6 | Kiwi, Prunes, Mango, Figs | Grade B | Not evaluated | 🌿 Best natural food options; prunes beat psyllium |
| 7 | SupraFiber / Yogurt with GOS | Grade B | Not evaluated | 🌿 Moderate evidence; needs more trials |
| — | Docusate (Colace) | Grade I | No recommendation | ❌ No clinical trial evidence of benefit |
| — | Inulin, Polydextrose, FOS | Grade I | Not evaluated | ❌ Insufficient evidence for constipation |
For most adults with chronic constipation, starting with PEG combined with lifestyle changes — drinking 8–10 glasses of water daily, eating 25–31 grams of fiber, and exercising regularly — gives the best long-term results. If your constipation persists beyond 7 days despite laxative use, or if you notice blood in your stool, see a doctor promptly.
References
- Rao SSC, Brenner DM. Efficacy and Safety of Over-the-Counter Therapies for Chronic Constipation: An Updated Systematic Review. Am J Gastroenterol. 2021;116(6):1156–1181. DOI: 10.14309/ajg.0000000000001222 | PubMed PMID: 33767108 | Free PMC Full Text
- Chang L, Chey WD, Imdad A, et al. American Gastroenterological Association–American College of Gastroenterology Clinical Practice Guideline: Pharmacological Management of Chronic Idiopathic Constipation. Gastroenterology. 2023;164(7):1086–1106. DOI: 10.1053/j.gastro.2023.03.214 — Also published in Am J Gastroenterol. 2023;118(6):936–954. DOI: 10.14309/ajg.0000000000002227
- Mayo Clinic Staff. Nonprescription laxatives for constipation: Use with caution. Mayo Clinic. Updated January 26, 2024. mayoclinic.org
Medical Disclaimer:Â This article is for informational purposes only and does not constitute medical advice. Always consult a qualified healthcare provider before starting any new treatment, particularly if you have underlying health conditions such as kidney disease, or if you are pregnant.
Affiliate Disclosure:Â This article contains Amazon affiliate links (rel=”sponsored”). ConstipationRelief.net earns a small commission if you purchase through these links, at no extra cost to you. Our recommendations are based solely on clinical evidence.
Read More on ConstipationRelief.net
- Fast Constipation Relief at Home: 12 Natural Ways That Actually Work
- 7 Natural Fiber Supplements for Chronic Constipation (Dosage & Side Effects)
- 5 Best Magnesium Supplements for Constipation (2026 Review)
- 9 Best Probiotic Supplements 2026
- Does Dehydration Cause Constipation? The Science-Backed Link
- 10 Best Natural Ways to Relieve Hemorrhoids and Constipation
- Yoga for Constipation Relief: 7 Science-Backed Poses
- Immediate Constipation Relief for Elderly at Home (Safe & Natural)
- Best Fiber Foods and Fiber Therapy for Gut Health
- 7 Natural High-Fiber Foods for Pregnancy Constipation Relief
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