I spend each week, wondering what to write about. Most of my articles are as a consequence of something I read over the Internet, questions asked by patients when they come to my pharmacy, or just something I was thinking about.
After listening to the various selections of kaiso on the radio, I was able to come up with this week’s article.
Yes we will look at laxatives and how they work and are they necessary.
Laxatives are medicines that are used to treat constipation. They can come in various forms that include liquids, tablets, or capsules, or they can be given via the rectum. Suppositories are pellet-shaped laxatives that are inserted into the rectum, via the anus. An enema is a liquid that is inserted into the rectum and lower colon, via the anus.
Laxatives are generally divided into four groups — depending on the way they work. Some laxatives work quickly, within 15 to 30 minutes, and some take one or two days to work. You should drink plenty of fluid when you are taking laxatives (8-10 cups per day).
Laxatives are usually taken for a few days until your bowel movements have returned to normal. But a few people need to take them long-term.
There are four main groups of laxatives that work in different ways. Each laxative often comes in various different brand names:
* Bulk-forming laxatives (also known as fibre supplements). For example, ispaghula husk, methylcellulose, sterculia. (Metamucil, Benefiber are examples). Unprocessed bran is a cheap fibre supplement.
* Osmotic laxatives. For example, lactulose, macrogols, phosphate enemas, and sodium citrate enemas.
* Stimulant laxatives. For example, bisacodyl, dantron, docusate sodium, glycerol, senna and sodium picosulfate.
* Faecal softeners. For example, docusate sodium, arachis (peanut) oil enemas, and liquid paraffin.
Constipation is when faeces (stools) become hard, and difficult or painful to pass. The time between toilet trips increases compared with your usual pattern. (Note: there is a large range of normal bowel habit. Some people normally go to the toilet to pass faeces two to three times per day. For others, two to three times per week is normal. It is a change from your usual pattern that may mean that you are constipated.)
Sometimes crampy pains occur in the lower part of your abdomen. You may also feel bloated and feel sick if you have severe constipation. Constipation can also be caused by your medication and may be caused by not eating enough fibre, or not drinking enough fluids. It can also be related to an underlying medical condition. In many cases, the cause is not always clear.
How do laxatives work?
Bulk-forming laxatives are sometimes called fibre supplements. They increase the bulk of your faeces. They partly work by absorbing water. The increase in the bulk of your faeces stimulates the muscles in your gut to squeeze faeces along and out of the body.
Fibre is the part of plant food that is not digested. It stays in your gut and is passed in the stools. Bulk forming laxatives can have some effect within 12-24 hours but their full effect may take several days to develop.
Osmotic laxatives work by retaining fluid in the large bowel by osmosis. This process dumps all the water into the bowel and causes the stool to become watery and soft. Epsom salts is an example of an osmotic laxative.
Lactulose is also considered a member of this class. Lactulose can take up to two days to have any effect so they are not suitable for the rapid relief of constipation. Macrogols (polyethylene glycol) act much faster, and can also be used in high doses to clear faecal loading or impaction. But stronger osmotic examples as Epsom salts clear rather quickly.
Stimulant laxatives stimulate the nerves in the large bowel. This then causes the muscle in the wall of the large bowel to squeeze harder than usual. This pushes the faeces along and out. Senna and Dulcolax are examples. These can cause pain though. They usually work within eight to 12 hours.
Taken at night you should feel the urge to go to the toilet sometime the following morning. However, you may try taking it at different times in the day to find the best time of day for you. Some people naturally have their bowel movements later in the day rather than in the morning.
Faecal softeners work by wetting and softening the faeces. This type works slower and is considered gentler. Docusate sodium is an example of this class. Although they wet the faeces, they do not cause the stool to be runny.
Instead of dumping the water into the gut, these absorb water from the intestines into the bowel and usually work within 24 to 48 hours.
Mostly, laxatives are taken by mouth. In some cases, your doctor may prefer to treat your constipation by giving medication via the anus. But the choice of laxative usually depends on: what you are comfortable with, the symptoms of constipation that you have, how severe your constipation is, the possible side-effects of the laxative, your other medical conditions, and cost.
As a general rule:
* Treatment with a bulk-forming laxative is usually tried first.
* If faeces remain hard despite using a bulk-forming laxative, then an osmotic laxative tends to be tried, or used in addition to a bulk-forming laxative.
* If faeces are soft but you still find them difficult to pass then a stimulant laxative may be added in.
If you are pregnant or breast-feeding there are a number of laxatives that are thought to be safe to take. If you do need to take a laxative when you are pregnant or breast-feeding you should always ask your doctor or pharmacist for advice about which one you should use.
Sometimes, an enema is needed in severe constipation and can be used to clear out the lower bowel (rectum). High doses of the macrogol osmotic laxatives are used to treat faecal loading and impaction (severe constipation) — this should be under the supervision and advice of a doctor.
Liquid paraffin used to be commonly used as a faecal softener. However, it is now not recommended, as it may cause side-effects such as seeping from the anus and irritating the skin, and it can interfere with the absorption of some vitamins from the gut. Also if drank too quickly, it may enter the lung area and cause pneumonia. This should be taken in milk and drank slowly.
Laxatives that are given via the rectum (suppositories or enemas) usually work within 15 to 30 minutes.
Laxatives very rarely cause serious side-effects. Common side-effects include flatulence, cramps, diarrhea, nausea, and bloating. Most of the side-effects can be avoided or reduced by starting off on a low dose and increasing the dose of oral laxatives gradually.
With bulk-forming laxatives — you may notice an increase in wind (flatulence) and abdominal bloating. This is normal and tends to settle down after a few weeks as the gut becomes used to the increase in fibre (or bulk-forming laxative).
Occasionally, bulk-forming laxatives can make symptoms worse if you have very severe constipation. This is because they may cause abdominal bloating and discomfort without doing much to clear a lot of faeces which are stuck further down the gut. See a doctor if you feel that bulk-forming laxatives are making your symptoms worse.
These medicines sometimes react with other medicines that you may take. So, make sure your doctor knows of any other medicines that you are taking, including ones that you have bought rather than been prescribed.
Sometimes we can use natural methods, such as golden syrup, black strap molasses or prunes.