Good for the short-term treatment of constipation.

But not for any other bowel or abdominal problem: a “good clear-out” is not a panacea.

Watch out for unnecessary treatment. There’s no need to self-medicate for an “infrequent bowel habit”, if it’s normal for you. And many cases of true constipation — difficulty in, or pain on, going — can be cured without medication. Try increasing your fibre and fluid intake, avoiding codeine-based painkillers, exercising regularly and not being in such a rush each morning that you suppress the urge to go.

If it doesn’t work and lifestyle measures don’t sort you out, there’s a vast array of alternatives, such as lactulose and ispaghula husk. Or you can attack from below with glycerine suppositories.

See your doctor if you have other symptoms such as weight loss, recurrent abdominal pain, the passage of blood or mucus, or bouts of diarrhoea alternating with the constipation.

Cost of treating Ex-Lax Senna costs £1.99 for 12x25mg tablets; Senokot £2.19 for 20x7.5mg tablets.