The Ingredients In Laxatives: What You Need To Know

Laxatives are a type of medicine used to treat constipation. They are available over the counter in pharmacies and supermarkets, and on prescription from a doctor. There are four main types of laxatives: bulk-forming, osmotic, stool softener, and stimulant. Laxatives work by softening stools, making them easier to pass, and by stimulating the bowels to get moving. They are usually taken orally in the form of pills, capsules, or liquids, but can also be administered as suppositories or enemas. While laxatives can provide relief from constipation, they should be used sparingly and in conjunction with lifestyle changes such as increasing fibre intake, drinking more fluids, and exercising regularly.

Bulk-forming laxatives

Common bulk-forming laxatives include psyllium (Metamucil), polycarbophil (FiberCon), and methylcellulose (Citrucel). They are generally considered the gentlest type of laxative and are the best option to try first, unless a doctor recommends a different type. They are also safe to use daily.

It can take 12 hours to up to three days for bulk-forming laxatives to work. It is important to drink plenty of water while taking them, as they can cause dehydration. They should only be used occasionally and for short periods of time, stopping once the condition improves. They should also not be taken within two hours of taking any medication, as they may impact how the body absorbs it.

Lubricant laxatives

Mineral oil laxatives work by coating the stool and the inside of the bowel with moisture, thus preventing the stool from drying out. It takes around eight hours for mineral oil to work, so it is recommended to take it before bedtime to avoid night-time bathroom trips. It is also advised to take mineral oil on an empty stomach, as it can interfere with the absorption of certain vitamins and nutrients. The recommended dosage for adults is 15 to 45 millilitres, but it is important to follow the instructions carefully and consult a doctor if needed.

Osmotic laxatives

Common osmotic laxatives include:

• Polyethylene glycol (PEG): This is an organic compound derived from petroleum that can be safely ingested to manage constipation. PEG is available over the counter under brand names like Miralax and GlycoLax. It is tasteless, odourless, and typically mixed with water or other fluids.
• Lactulose: This is a synthetic sugar solution that acts as an osmotic laxative by drawing water into the colon. It is often prescribed to treat chronic constipation and hepatic encephalopathy. Lactulose is available by prescription under brand names like Cephulac, Duphalac, and Kristalose.
• Sorbitol: This is a non-absorbable sugar with an action similar to lactulose. It is available in both over-the-counter and prescription versions, including brands like Arlex and GeriCare.
• Magnesium citrate: Magnesium citrate is a salt form of magnesium combined with citric acid. The salts help draw water into the colon. OTC versions include Citrate of Magnesia, Citroma, and LiquiPrep.
• Magnesium hydroxide: This is a milder form of magnesium sold under the brand name Milk of Magnesia, which is available over the counter. It is also used as an antacid.

It is important to drink plenty of water while taking osmotic laxatives to improve their effectiveness and reduce the possibility of side effects such as gas and cramps. However, overuse of osmotic laxatives can lead to dehydration and the loss of important electrolytes like sodium, calcium, and potassium, which are essential for regulating key bodily functions.

Stimulant laxatives

The active ingredients in stimulant laxatives are usually either senna (also known as sennosides) or bisacodyl. Senna is also known to cause urine to turn a brownish-red colour.

• Senexon (sennosides)
• Fletcher's Castoria (sennosides)
• Senokot (sennosides)
• Black Draught (sennosides)
• Feen-A Mint (bisacodyl)
• Correctol (bisacodyl)
• Dulcolax (bisacodyl)
• Carter's Little Pills (bisacodyl)

Do not use stimulant laxatives for more than a week unless advised by a doctor. Understand that they can be habit-forming and can be harmful to your bowels if used for an extended period of time. Do not give stimulant laxatives to a child under the age of 6 unless instructed to do so by a pediatrician.

Prescription laxatives

There are four classes of prescription laxatives: osmotic laxatives, prokinetic agents, secretagogues, and opioid antagonists. Osmotic laxatives, available both over-the-counter and by prescription, draw water into the bowel to help soften stool so it passes more easily. Osmotic laxatives that are only available by prescription include Cholac/Generlac (lactulose), which is approved for constipation, including that related to barium retention.

Prokinetic agents, of which Motegrity (prucalopride) is the only drug currently available in the United States, cause the gastrointestinal tract to contract and push materials through. Motegrity is approved for chronic idiopathic constipation in adults.

Secretagogues, such as Lubiprostone (Amitiza) and Plecanatide (Trulance), pull water into the bowel to soften the stool, like osmotic laxatives, but through a different mechanism of action. Lubiprostone is approved for chronic constipation in adults, including constipation from IBS-C in adult women. Plecanatide is approved for chronic constipation in adults.

Finally, opioid antagonists are medications that have been developed to relieve opioid-induced constipation by partially blocking the actions of opioid medications. These include Relistor (methylnaltrexone), Movantik (naloxegol), and Symproic (naldemedine).

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