By Caroline Gerdes

The Best Laxatives

The best laxative should be effective, fast-acting, and as gentle as possible on your body. After speaking with doctors and reading through peer-reviewed medical research, we narrowed a starting pool of 62 products down to three top picks — best-selling products with few side effects when taken as directed.

The 3 Best Laxatives

The Best Laxatives: Summed Up

Phillips' Milk of Magnesia
MiraLAX
Phillips' Laxative Caplets
Best for Fast-Acting Relief
Best for Sensitive Stomachs
Most Convenient
Price
$25 for roughly 34 doses
$24 for roughly 45 doses
$14 for roughly 33 doses
Price per dose
74 cents
53 cents
42 cents
Form
Liquid
Liquid
Caplets
Type
Hyperosmotic
Hyperosmotic
Hyperosmotic
Timeframe
30 mins to 6 hours
1-3 days
30 mins to 6 hours

Phillips’ Genuine Milk of Magnesia (Original)

Best for
Fast-Acting Relief

Phillips' Genuine Milk of Magnesia Original
Pros
Works quickly
Low risk of side effects
Cons
Chalky aftertaste

Why we chose it

Works quickly

To get back to “regular” as quickly as possible, we recommend Phillips' Genuine Milk of Magnesia. The low-risk formula works fairly quickly: according to its packaging, it typically produces a bowel movement in under 6 hours, and sometimes as soon as 30 minutes. One dose is 2-4 tablespoons (or one to two gulps) and the product is meant to be taken once daily for no more than seven days.

Low risk of side effects

Its active ingredient, magnesium hydroxide, is recommended by the American Gastroenterological Association as a good preliminary treatment option for constipation.While prolonged use of a magnesium laxative can lead to an electrolyte imbalance (in turn leading to diarrhea and stomach cramps), Phillips’ Genuine Milk of Magnesia Original is gentle enough when used as directed. Side effects are rare, but can include flushed skin, and drowsiness. Because all laxatives can lead to loss of fluids, it’s also important to drink plenty of water to avoid dehydration.

Points to consider

Chalky aftertaste

The main drawback is that Phillips’ Genuine Milk of Magnesia Original is rather unenjoyable to swallow. It’s a thin, slightly viscous liquid that you pour into a measuring cap before swallowing. While it has no discernable odor or taste, we found the texture extremely unpleasant: it left a chalky residue in our mouths that was hard to wash out. We even refrigerated the bottle for six hours to see if it would become any more palatable, and while this made the liquid a bit easier to swallow, it didn’t help with the aftertaste. Still, it’s so effective that you likely won’t need to take it for very long to see the benefit.

MiraLAX Laxative Unflavored

Best for
Sensitive Stomachs

MiraLAX Laxative Unflavored
Takes longer to kick in, but tasteless and with fewer side effects
Pros
Tasteless and dissolves easily
Doctor-preferred
Cons
Can take days to work

Why we chose it

Tasteless and dissolves easily

MiraLAX, our pick for those with sensitive stomachs, is notably more palatable than Phillips’ Milk of Magnesia. It comes as a white powder that can be mixed into any beverage (hot or cold) and, apart from a slight mineral undertone, tastes like nothing.

Doctor-preferred

Polyethylene glycol, the active ingredient in MiraLAX, is also more likely to be recommended by doctors than magnesium-based products like Phillips’. Dr. Leila Kia, Assistant Professor of Medicine at Northwestern University, told us that when fiber, exercise, and water won’t do the trick, “My first line laxative is polyethylene glycol 3350 (or Miralax). It is safe, effective, and can be titrated up or down to get the desired effect. I start with 17 grams of powder dissolved in 8 ounces of water, once daily.”

Dr. Mukherjee, echoed Kia’s preference, explaining that MiraLAX is often preferred by doctors because of the risk of electrolyte disturbance that comes with prolonged use of magnesium-based products. So if you’re looking for a laxative that’s as safe and gentle as possible, MiraLAX is it.

Points to consider

Can take days to work

Like Phillips’, MiraLAX is a hyperosmotic laxative, although it relies on polyethylene glycol rather than magnesium to draw water into the intestine. MiraLAX states that it “generally produces a bowel movement in 1 to 3 days,” compared to the six hours advertised by Phillips’ Milk of Magnesia. So if you need relief as soon as possible, Phillips’ is a better bet.

Phillips’ Laxative Caplets

Most
Convenient

Phillips' Laxative Caplets
A pill with the same active ingredient as Phillips' Milk of Magnesia
Pros
Easy to take
Fast-acting
Cons
Not verified by FDA

Why we chose it

Easy to take

If you don’t want the hassle of measuring out doses (or gulping down milk of magnesia), Phillips' Laxative Caplets may be preferable. A daily serving is 2-4 pills; each is roughly the size and shape of a Tylenol tablet. Note that they’re uncoated, so we’d suggest swallowing quickly — otherwise, they’ll start to dissolve, leaving behind that same chalky milk of magnesia taste.

Fast-acting

In its FAQ, Phillips’ says the caplets typically start working in “one-half to six hours,” the same time frame as its milk of magnesia. They’re a magnesium-based drug, so they come with the same caveat about prolonged use as the brand’s liquid medication but are quite gentle when used as directed.

Points to consider

Not verified by the FDA

Unlike our other two picks, Phillips’ Laxative Caplets are classified as a dietary supplement rather than a drug. This doesn’t mean they aren’t effective, just that they contain a few extra binding ingredients that cause the product to fall outside the FDA’s very narrow definition of “laxative drug.” The upshot is that the caplets’ efficacy claims haven’t been vetted by the FDA. We weren’t overly concerned by this — Phillips’ has a solid reputation, and the caplets have a 4.4 star average on Amazon — but if you don’t want to take the gamble, we’d suggest one of our other top picks.

Guide to Laxatives

How to find the right laxative for you

Try natural remedies first

Diet, exercise, getting enough sleep, and drinking plenty of water are the best medicine when it comes to treating constipation. Dr. Kia typically recommends “a trial of soluble fiber, along with increased water intake” before even the gentlest OTC laxative, since all drugs can have side effects.

Set a timeframe

Our recommended options work on different schedules: Phillips’ magnesium hydroxide tends to yield results in under six hours, while MiraLAX’s polyethylene glycol works over a course of days. Your level of urgency should help determine your drug of choice, with stimulant laxatives (such as Dulcolax and Ex-Lax) as a backup if gentler alternatives fail.

Listen to your body, and see a doctor if necessary

Just because certain laxatives are gentler doesn’t mean they’re great for everyone. If you’re experiencing pain or discomfort, it’s best to immediately discontinue use. Dr. Kia cautions that “If someone has tried over-the-counter laxatives without success, it’s a good idea to see a doctor to discuss other possible treatments or further testing. If someone experiences any of the following symptoms, they should also consult a doctor: rectal bleeding, abdominal pain, waking up at night with the urge to have a bowel movement, weight loss, sudden change in type and frequency of bowel movements, or a family history of colon cancer.”

Laxatives FAQ

What are the different types of laxative and how do they work?

The term “laxative” actually covers an array of options:

Lubricant laxatives work by making stool slippery and easy to pass (often via ingredients like mineral oil or castor oil). But if taken frequently, these products can interfere with your body’s absorption of fat-soluble vitamins. This probably isn’t a big deal if you’re just popping a daily multivitamin, but it’s a little riskier if you’re on prescription meds — and there are plenty of other types of laxatives that don’t pose this problem.

Emollient laxatives (aka stool softeners) present a different drawback: The Mayo Clinic explains that they don’t necessarily cause bowel movements to happen. Instead, they just soften the stool to prevent straining when you do go. This might be why Consumer Reports found, in its 2008 laxative review, that “if you have chronic constipation, [stool softeners] probably won’t help much.”

Stimulant laxatives (which include brands like Dulcolax and Ex-Lax) work by stimulating the colon. They’re effective, but also pretty harsh on the body, since they “stimulate the intestines by irritating them,” according to Dr. Mukherjee. Regular use can also cause dependency: your colon can forget how to contract on its own, leaving your body unable to produce bowel movements without assistance.

Hyperosmotic laxatives (which include our top picks) are generally safer for short-term constipation relief than lubricant or stimulant laxatives, and more effective than stool softeners. They work by drawing water into the intestine, encouraging bowel movements and making stool easier to pass. But as with any drug, consult your doctor if you have questions or notice side effects — and remember to drink lots of water.

How can I tell if I’m constipated?

The American College of Gastroenterology reports “at least 2.5 million doctor visits for constipation in the USA each year,” so it’s indeed a widespread complaint. But is your discomfort a genuine medical issue? If you meet two or more of the following criteria, it might be time to reassess your dietary habits:

  • Fewer than three bowel movements per week.
  • Passage of lumpy or hard stools at least 25% of the time.
  • Presence of straining at least 25% of the time.
  • Sensation of incomplete evacuation at least 25% of the time.
  • Sensation of blockage at least 25% of the time.
  • Need to use manual maneuvers to facilitate a bowel movement at least 25% of the time.

How can I prevent constipation?

Dr. Mukherjee told us that the best long-term treatment for constipation is developing good bowel hygiene. “The most common reason [for] constipation [is] a lack of dietary fiber, hydration, and exercise. To achieve the best the body can do, we need to have a good bowel hygiene. That would include a scheduled exercise and sleep pattern. It also means [having] regular nutritious meals with fiber and adequate hydration,” he said. “If these things can be controlled early on, most of the problems of long-term constipation can be alleviated.”

More Health & Wellness Product Reviews

Laxative isn’t the only thing your body needs to function at its best. Check out our top picks for other ways to maintain a healthy inner balance:

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