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Treatment > Medications

Do over-the-counter laxatives have a quick effect?

Dr. med. André Sommer

Dr. med. André Sommer

Constipation can have various causes. A change in living conditions while traveling or a change in diet can be the reason your bowel movements stop for a short period. A low-fiber diet or insufficient fluid intake can also be responsible. But even with metabolic disorders, a lack of exercise or as a side effect of medication, bowel movements can be less frequent, harder or painful.

If natural measures are not enough, doctors and pharmacists can recommend various laxatives. What types of laxatives are there, how are they used and what should be considered when using them?

When are laxatives used?

Laxatives are used for severe constipation when other measures are ineffective. Depending on the mechanism of action, different groups of laxatives are distinguished, which have a different potency.

Basically, laxatives can be used for both acute and long-term (chronic) constipation. However, the doctor should always carry out a diagnosis beforehand. The reason is that there can also be an intestinal obstruction underlying the constipation. This is a medical emergency that should never be treated with laxatives on your own (contraindication). In addition, some laxatives should only be used for a limited period of time because you can become accustomed to them and lose fluid and blood salts (electrolytes).

When does constipation occur?

Constipation occurs when you have bowel movements less than three times a week. In addition, the stool has a rather lumpy or hard texture (consistency). Elimination of stool (defecation) is often painful, delayed, or requires heavy pressing. If these symptoms persist for more than three months at a time, chronic constipation is considered.

Temporary (acute) constipation is more likely to occur when the daily rhythm is changed, for example when traveling or during shift work.

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Which general measures help against constipation?

Laxatives are not necessary for every case of constipation. It often helps to change your diet and eat more fiber. These are found, for example, in whole grains as well as in fruits and vegetables. It is important to drink plenty of liquid in addition to the fiber, otherwise the indigestible food fibers will swell and thus increase constipation. As a guideline you need 1.5 to 2 liters per day. This corresponds to about six to eight large glasses (250 ml).

Movement in the form of walks and sport can promote the movements of the intestine (intestinal motility) and thus cause the stool to pass through the intestine more quickly (passage). In addition, those affected should not suppress the urge to defecate, otherwise the passage of food through the intestine will take longer due to a habituation effect.

According to some experience reports, an abdominal wall massage for about ten minutes before getting up and drinking a glass of cold water on an empty stomach can stimulate digestion.

What should be considered before using laxatives?

Laxatives should not be used without advice from a doctor or pharmacist. In most cases, a physical exam with a thorough doctor’s discussion about eating habits and medication makes sense. Various other diseases such as diabetes mellitus and hypothyroidism can lead to constipation. Therefore, you should be examined by a physician for long-standing constipation and not simply take laxatives yourself. Treating the underlying condition would address the root cause of the problem, while laxatives would only treat the symptoms.

In addition, in the case of metabolic disorders such as diabetes and hypothyroidism, it is very important to set the metabolism correctly again, otherwise serious consequential damage can result. With prolonged constipation an inflammatory disease (e.g. Crohn's disease or ulcerative colitis) or a malignant disease of the intestine should also be ruled out.

You may also need blood tests for the stool or a colonoscopy. Acute constipation should always be clarified with a doctor. The reason is that for some causes of acute constipation, uncontrolled use of laxatives can be dangerous and may worsen the clinical picture.

In addition to taking the laxatives, patients should continue to take the general measures outlined above, as laxatives should not be taken for long periods of time.


Self-treatment with laxatives is not recommended. The doctor should first clarify the cause so that complications or side effects do not occur.

What laxatives are there?

Filling and swelling agents If the dietary fiber is insufficient, fillers and swelling agents can be used. They are considered to be relatively gentle laxatives: They bind water and make the stool more voluminous and softer. For this effect, you can, for example, stir flaxseed or psyllium husk into your muesli. The material needs enough liquid to swell. Therefore, you should drink at least one glass of water with each serving and drink 1.5-2l per day.
Laxatives with osmotic effects Osmotically active laxatives act by influencing the fluid distribution in the intestine. Their so-called osmotically active ingredients bind liquid so that the intestine draws less liquid from the stool. This keeps the stool softer. Adequate hydration must also be ensured for laxatives with osmotic effects. The active ingredients of the osmotic laxatives are, for example, soluble large molecules (for example macrogol) or non-absorbable sugars and sugar alcohols (for example lactulose and sorbitol). Lactulose and sorbitol can, however, lead to increased flatulence. In very rare cases, macrogol leads to electrolyte derailments. Therefore, it is sometimes taken directly with electrolytes.
Fast-acting laxatives For quick, short-term colon cleansing, salt-based laxatives such as

Epsom salt or Glauber's salt can be used. However, they can be partially absorbed by the body and upset the electrolyte balance. Experts advise against these laxatives if you have previous diseases such as high blood pressure, heart failure or kidney dysfunction.

Stimulating laxatives Laxatives that stimulate the intestine help in particular when slow intestinal passage is the cause of constipation. Active ingredients such as sodium picosulfate and bisacodyl ensure that liquid is actively released into the intestine and that intestinal activity increases. However, cramping and abdominal pain can increase as they affect the smooth muscles of the intestine. Since salts such as potassium and sodium are increasingly excreted with the liquid, electrolyte disturbances can occur. For this reason, these laxatives should only be taken for a short time.
Suppositories and enemas If stool has stuck in the last part of the large intestine, these fecal balls or fecal stones usually make it difficult to defecate. In such cases, the stool can either be carefully removed with your finger or, for example, softened and emptied with the help of paraffin-containing suppositories and enemas (klysma, enema).

What laxatives can be used for IBS?

Since irritable bowel syndrome is a chronic condition, laxatives that are too aggressive should not be used. General measures such as adequate hydration, a high-fiber diet and regular exercise are therefore of great importance. Herbal laxatives such as psyllium husk can increase the digestive effect. If the main problem is not being able to press the stool out, enemas or suppositories are also possible.

If these measures are not sufficient, a doctor can advise which laxatives are useful. The osmotic laxative macrogol is mostly used because it causes less flatulence than sugar and sugar alcohols. Various new active substances (e.g. lubiprostone, linaclotide) are also being researched. There is also initial evidence that probiotics that contain beneficial bacteria such as some bifidobacteria can have a beneficial effect on irritable bowel syndrome.

Can laxatives help you lose weight?

In Internet forums you can sometimes find the tip to use laxatives such as Glauber's salt to lose weight. The theory behind this is that the accelerated passage through the intestine means that the body has less time to absorb nutrients. In fact, such laxatives primarily result in a loss of water and salts. This loss is shown briefly on the scales, but it can also cause serious side effects such as a lack of fluids or arrhythmia. The use of laxatives does not replace a balanced, healthy diet. Often, a yo-yo effect is noticeable soon after weaning and the weight increases again. For these reasons, laxatives are not suitable for losing weight.

Can laxatives help with fasting?

Many fasting protocols provide for colon cleansing during fasting. This can be done either with laxatives or with enemas. However, because such a radical colon cleansing during fasting can lead to circulatory problems and other complications, it should only be done after consultation with a doctor.

What are the risks of laxatives?

Strong laxatives such as osmotic or stimulating laxatives can cause changes in the electrolytes in the blood due to the increased water excretion, so that, for example, there is too little sodium or potassium in the blood. In addition to cardiac arrhythmia, a potassium deficiency can also lead to sluggish bowel movements and, in turn, constipation. This often creates a vicious circle of administration of laxatives and constipation. Basically, laxatives should therefore only be used under medical supervision and for a limited period of time.

If laxatives are used for a longer period of time, the body can get used to them. This means that constipation occurs again and again without further laxative administration and those affected no longer have the option of maintaining normal bowel movements without the medication. However, the latest studies show that this so-called habituation effect is not as pronounced as has been suspected for a long time.

When else are laxatives used?

Medications such as antidepressants or opiates and even laxatives themselves can cause constipation. For this reason, some medications such as opiates are often prescribed together with laxatives to reduce the side effects.

Children often hold their stool as a result of a painful bowel movement experience. However, this behavior increases constipation. In adults too, spasm of the sphincter can lead to so-called “outlet obstruction”. The nerve supply to the intestine is disrupted and painful constipation occurs again. This vicious cycle can sometimes be broken by using mild laxatives.

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Dr. med. André Sommer

Dr. med. André Sommer

I’m André, a medical doctor from Berlin. Together with a team of medical doctors, nutritionists and data scientists we empower people to understand digestive issues with our app Cara Care.

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