All you need to know about laxatives
Hard, lumpy stools? Straining on the loo? Less than 3 bowel movements per week? Feeling as if your bowel never really empties? Constipation is common and laxatives may help, yet misconceptions and taboo abound.
Why constipation matters
During the ‘Great Stink’ of 1858, the River Thames became so constipated with sewage that Parliament was interrupted, Queen Victoria had to abandon her pleasure cruise and cholera was rife. When your gut is constipated, pain, bloating, loss of appetite, fatigue and rectal bleeding can result.
Chronic constipation can result in a serious condition called faecal impaction: a mass of dry, hard poo obstructing the bowel.
How laxatives can help
When the colon is stretched by stool, millions of nerve fibres within the gut walls are activated, causing the gut to contract, helping the poo to move along. Larger stools stretch the gut more.
Hence poo is easier to pass if it is big, but not too big. Bulking agents such as wheat bran, oat bran and fybogel increase the volume of the poo because the fibre they contain cannot be digested by gut bacteria.
Larger stool will be difficult to pass if it is hard and dried, so it’s important to drink plenty of water (a healthy poo contains up to 75% water). Other laxatives such as lactulose moisten poo, and increase its volume, by drawing water into the bowel.
Softeners, stimulants and suppositories
Senna is a herb that has been used in medicine for millennia. It stimulates nerves in the gut, increasing gut contractions. Sodium docusate acts in a manner similar to detergent, softening the faeces. Glycerol suppositories act as a lubricant and stimulant, since glycerol is a mild irritant in the gut.
All laxatives should be taken under medical advice: many can cause abdominal cramping, wind, or diarrhoea, as vividly depicted in Roald Dahl’s ‘Goldie Pinklesweet’ poem. Prolonged usage can result in ‘lazy bowel syndrome’ or a need for ever-increasing dosages as tolerance develops.
Teaching an old dog new tricks?
What do serotonin (the happy hormone), botox (the anti-wrinkle jab) and colchicine (a gout medicine) have in common? They are all being investigated as possible treatments for constipation.
Not just a brain chemical, 90% of the total body serotonin is in the gut, released from nerves to stimulate gut contraction. In clinical trials, a serotonin-like drug called Zelnorm increased bowel movements, though it is used with caution.
Botox is well-known as a drug that inhibits muscle contraction: it is useful in preventing wrinkles, reducing muscle spasms and relieving writer’s cramp. It is being tested in cases of constipation caused by an over-tight muscle in the rectum: relaxing this muscle would allow the poo to pass. However, the effects of botox can be short-lived, and incorrect dosing can result in incontinence.
Colchicine, derived from the autumn crocus or meadow saffron, is a useful gout medicine. Though it can cause diarrhoea, it may be useful at the right dose in treating constipation.
Food as laxative?
Prunes, rhubarb and cabbage can relieve constipation, though wheat, rye and oats have higher faecal-bulking potential; carrots, bananas, eggs and black tea can constipate.
A varied diet, plenty of water and exercise and minimal use of constipating drugs such as morphine and codeine may limit the need for laxative medicines.