Best Laxative
From the Medical World

If you have intractable constipation, you need to know what the best laxative from the medical world is, and how it works.

As you know, this site is all about natural constipation remedies. Laxatives, obviously, are not.

However, they can be instrumental in the management of acute constipation crises.

I do not think laxatives are evil. Things are not black and white, food and herbs on one side (the good guys) and medication on the other side (the bad guys). I used to think so when I was studying herbalism.

And then, clinical experience taught me the following:

  1. Food and herbs are very good for prevention;
  2. Food and herbs are very good for chronic and lingering conditions;
  3. Food and herbs have limited uses for acute, painful crises. They do provide relief, but often they are not enough to eliminate the crisis completely, especially for constipation.

In certain situations, they work as a team and they each have a particular role to play.

Click on the following link to see a list of the best natural constipation remedies.

When should you use laxatives?

You may need laxatives if you are stuck in situation #3 described above, that is to say if you have intractable constipation that has not responded to nutrition, herbs or supplements so far.

If you haven’t gone to the toilets for days and you feel you may be getting close to a fecal impaction, you need to act fast, and you need to know what best laxative you can grab from the pharmacy’s shelves.

You may have tried yellow dock, magnesium, vitamin C, prune juice, or olive oil, or all of those combined. But you may have tried them too late in the process. You are now very tempted to grab that box of MiraLAX.

I am fine with the MiraLAX approach as long as once the crises is averted, you take those few days of relief as an opportunity to put a natural constipation remedies program in place. Your goal is to get out chronic constipation, and finally move into prevention with just a few occasional mild bouts. Laxatives can sometimes help us get there.

The next question you may be asking yourself is "of all the products on the market, which one is the best laxative?". And the answer is not black and white.

No overarching best laxative

You will find different classes of laxatives on the market, either delivered over-the-counter or with a prescription.

They isn't any overall "best laxative", each have a role to play, and it is important to understand the distinction between the following types. Once this is understood, we can discuss what the best laxative is.

1. Bulk-forming agents

The proponents of the “get more fiber” message will strongly suggest that a particular fiber supplement (say wheat bran) is the best laxative you can ever find. They contain fiber-like substances that expand with water and provide “bulk” to your feces. They are like sponges. This bulk, in theory, applies more pressure to the stretch receptors of your intestine and forces fecal matter to move.

Which, when you think about it, is a bit of a strange objective. If you have a tendency to be backed-up with overstretched gut muscles, do you really want to add more bulk to the traffic jam down there?

Fibers can be found in natural forms :

  • Psyllium (the husk of the seeds of Plantago ovata) – brand name Metamucil. Psyllium provides “soluble fibers”
  • Wheat bran (the husk of the wheat cereal) – can be purchased as food supplement. Wheat bran provides “insoluble fibers”.

Insoluble fibers pass through the digestive tract undigested. They are abrasive to those who have inflammatory bowel issues, and according to the latest research, they probably are abrasive to most of us too.

Psyllium on the other hand is composed of “soluble fibers” that are digested by our gut flora. In other words, they have the advantage of being a prebiotics, being less abrasive and feeding our gut flora.

Fibers can also be found in a synthetic form :

  • Calcium polycarbophil, sold over the counter under many names (Fibercon, Fiber tabs, etc);
  • Methyl cellulose (derived from cellulose, a constituent of plant cell walls) – brand name Citrucel.

Bulk laxatives are generally taken with lots water so that they can expand in your gut and do their “stretching” work. If you don’t take enough water, you run the risk of bloating and bowel obstruction, as the fibers will not expand enough and will form a hard mass.

Here is my take on those supplements :

  • Fix your nutrition first : bulk-forming agents are only needed if your nutrition severely lacks vegetables and fruits. As I explained in other articles, whole grains can be problematic for lots of constipated people so I am not counting them as fiber source here. If your food is so lacking in vegetable and fruits that you need those supplements, sorry to say but in the long run constipation will be the least of your problems. You will face severe nutritional deficiencies that will lead to more serious and degenerative diseases.
  • Only use bulk laxatives for maintenance: they are counterproductive if you are already seriously backed-up. They will add more bulk to an already overstretched colon. They may have a “maintenance” role to keep you regular once you are out of a crisis. But again, you should be incorporating vegetables and fruits in your life, lots of them rather than relying on fiber supplements.
  • Psyllium (Metamucil) has at least the advantage of containing soluble fibers that can feed our gut flora and are a bit less abrasive to the gut.

To summarize, you should not need to use those supplements when you have control over what you ingest and you can prepare your own food, which is hopefully most of the time. If you have to travel for instance and you will have no control over food preparation, I would favor psyllium supplements over the rest. To me, psyllium is the best laxative in the bulk category.

To finish this chapter, let us keep in mind the big picture. Studies have shown that fibers, when provided as part of a diet containing lots of vegetables and fruits, have a health protective effect. But when they are taken as a supplement, studies(1) show that they lose that benefit. They can moreover bind with many nutrients in the gut and prevent absorption of those nutrients.

I will provide 3 telling quotes from the “Fiber and colorectal diseases: separating fact from fiction” study published in the World Journal of Gastroenterology (and mentioned in the references section of this article):

“A strong case cannot be made for a protective effect of dietary fiber against colorectal polyp or cancer. Neither has been found to be useful in chronic constipation and irritable bowel syndrome.”

“The formation of large amounts of faecal material can actually have a detrimental effect on the patient. Faeces that is bulky and hard is more difficult to evacuate in a patient with a pre-existing evacuatory problem.”

“The need to evacuate large bulky stools frequently may also give rise to various anorectal disorders including hemorrhoids and anal fissures.”

Based on this, and against popular and medical advice, I believe that fibers do not belong to the best laxative category.

2. Osmotic laxatives

Just like bulk laxatives, an osmotic laxative draws water into your gut, but in a different way.

In the previous section, we saw that bulk laxatives act as sponges. You ingest them with lots of water, they expand, and supposedly bring that moisture down into your gut.

Osmotic laxatives, on the other hand, act like water magnets. They are absorbed, make their way into the gut, and once there, they draw water from the gut mucosa into the gut itself where the fecal matter is sitting.

They are, in my mind, more effective than bulk laxatives because they bring fluids everywhere in the gut and not just "before the traffic jam" where the sponge will sit. They will also make the traffic jam itself more fluid. They are still not enough to evacuate a serious plug (impaction) though.

Osmotic agents include the following substances :

  • Polyethylene glycol (PEG or PEG 3350), which is today the most popular osmotic laxative in the medical world, because it has been shown to be effective in many constipation studies over a placebo(2). PEG can sometimes cause nausea, bloating, gas and diarrhea if overused. This is sold under the brand names MiraLAX, GlycoLax, GoLYTELY, Carbowax, Fortrans, TriLyte, Colyte, Halflytely, Macrogol, MoviPrep
  • Lactulose, a type of sugar that draws water into the gut. It is sold under the brand names Cephulac, Chronulac, Constilac, Constulose, Duphalac, Evalose.
  • Sorbitol, another type of sugar, usually sold under the generic name "sorbitol".
  • Magnesium hydroxide (see the article on magnesium and constipation), sold under the form Milk of Magnesia, and under the brand names Phillips' Milk of Magnesia, Dulcolax Milk of Magnesia, Ex-Lax Milk of Magnesia. As explained in my magnesium article, I am in favor of using pure magnesium supplements instead of milk of magnesia. Some milk of magnesia products contain aluminum, a substance implicated in the development of Alzheimer’s disease.

As far as I can see, none of those laxatives cause long term negative consequences on health (except the milk of magnesia containing aluminum and possibly increasing your risk of Alzheimer’s disease).

Which does not mean you should rely on osmotic agents to become regular. But in my opinion, they can be a useful tool to give you a break as you put a longer-term sustainable strategy in place, and that strategy will of course not include any of those chemical agents.

If I had to pick one substance as best laxative, I would go with magnesium first (read my article on magnesium and constipation) and PEG as second best laxative.

Note that osmotic laxatives take a bit of time to work, usually half a day to a day. So if you take them, say, in the afternoon, you should expect an effect the next morning or more likely the next afternoon. Plan accordingly in terms of logistics, making sure you will be near a toilet once the effect starts to kick in.

3. Stimulant laxatives

These laxatives are the harshest of all, because they provoke muscle contractions. They are irritant substances that kick the gut muscles into movement. Note the difference between the other two classes which are passively drawing water, and this class which actively and mechanically gets things moving. The side effects are usually pain and cramping.

Additionally, stimulant laxatives prevent water from being reabsorbed by the gut mucosa, thus keeping more liquid with the fecal matter.

Stimulant laxatives include the following substances:

  • Senna extract, from the senna plant. Even though this substance comes from a plant, it is not gentle at all. This is sold under the brand names Ex-Lax, Senokot, Senexon.
  • Other medicinal plants such as Cascara sagrada or Buckthorn. Again, even those are plant based, they are not gentle, balancing plants.
  • Castor oil, which can sometimes bring bouts of explosive diarrhea.
  • Bisacodyl, sold under the brand names Dulcolax, Durolax, Fleet, Alophen, Correctol, Carter's Little Pills.

I recommend you avoid those as much as possible, knowing that combining both osmotic and stimulant laxatives is often required when there is impaction. So in some cases, you may not be able to avoid it.

I am not sure I can pick the best laxative in this category. Some people believe senna is best, others swear by bisacodyl. You will have to experiment by yourself if you get to that point, and see which one in the best laxative for you: providing the best results with the least side effects (cramping).

4. Enemas and suppositories

Those two options may provide help in getting rid of a fecal impaction. A lot of people are hesitant to insert anything in their rectum. But enemas and suppositories are a valid tools, even for children, so do not discard them for emotional reasons.

You can find for instance Dulcolax laxative suppositories that are acting much faster than the version taken by oral route. But you can also try glycerine suppositories, which do not contain any of the laxative substances mentioned above, but contain glycerine, an irritant which triggers peristalsis when in contact with the colon mucosa. It does not moisten the stools, but it will have a stimulant effect, getting things to move.

Of course, I would not rely on enemas and suppositories on an ongoing basis. I see those as tool to treat a severe constipation case, in conjunction with the laxative categories mentioned above.

Use suppositories or enemas if:

  • You need something fast acting. You cannot avoid to wait longer or things will get much worse (possibly impaction). Take dulcolax as suppository instead of orally, or try a glycerin suppository, or ask your pharmacist which enema he or she would recommend.
  • You are already impacted. In which case, you may not have a choice. You will need to take laxatives via both the oral and anal route. Work with your doctor to figure out what combination to use.

In terms of best laxative, I would suggest you start with suppositories, which are a lot less invasive than enemas, and much easier to administer.

Best laxative based on severity

If you need laxatives to give you a break, to give you time to gather your thoughts regarding natural approaches to your condition, I suggest the following:

Constipation severity
Mild to moderate, chronic
Nutrition + one or several of : yellow dock, prune juice, olive oil, magnesium vitamin C.

If you have to eat a sub-optimal amount of vegetables and fruits due to travel for instance: add psyllium (bulk laxatives).
Remedies mentioned in the previous row + possibly one osmotic agent (PEG or high doses of magnesium)
Osmotic agents (PEG or high doses of magnesium) + Stimulant laxatives (Senna or bisacodyl)
Work with your doctor. It will likely be osmotic agents + possibly stimulant laxatives + enemas/suppositories + possibly manual disimpaction.


Laxatives, just like any other drugs, are neither good nor bad. They are good when we really need them, and bad when we abuse them. They have their role to play in acute constipation crises. They allow people to get out of what could sometimes be a vicious circle, and get back on track to find a longer lasting natural approach.

In this article, we saw that there is not necessarily one best laxative, but a suite of tools for emergency situations.

Laxatives are never an end into themselves. They do not constitute a long term strategy.

But they cut you a break and enable you to experiment with and stabilize your natural constipation program.

If you need to take them once in a while, do not feel guilty. There won’t be any long term consequences to this choice. Regular, constant use is another story. We will address laxative addiction and abuse in a separate article.

References for "Best Laxative"

(1) Tan KY, Seow-Choen F. “Fiber and colorectal diseases: separating fact from fiction.” World J Gastroenterol. 2007 Aug 21;13(31):4161-7.

(2) Leung L, Riutta T, Kotecha J, Rosser W. “Chronic constipation: an evidence-based review.” J Am Board Fam Med. 2011 Jul-Aug;24(4):436-51.

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