EVIDENCE BASE FOR OVER-THE-COUNTER MEDICATION Before medicines are recommended it might be useful to discuss if stress is a factor and if this can be avoided. Dietary modification has shown to be effective for some patients. Suspected food products must be excluded from the diet for a minimum of 2 weeks and then gradually reintroduced to determine if the food item triggers symptoms.

EVIDENCE BASE FOR OVER-THE-COUNTER MEDICATION (Continued) Antispasmodics are considered first-line pharmacological intervention for IBS, these include mebeverine, alverine, hyoscine and peppermint oil. Bulk-forming and stimulant laxatives can be used to treat constipation-predominant IBS and loperamide for diarrhoea-predominant IBS. Both laxatives and diarrhoeals can be taken on a regular basis using the lowest effective dose.

Alternative treatments. Antispasmodics. Alternative treatments.

1. ANTISPASMODICS 1.1. HYOSCINE BUTYLBROMIDE (BUSCOPAN) It is a quaternary derivative of hyoscine so it does not readily cross the blood-brain barrier and therefore sedation is not normally encountered, although it might cause dry mouth and constipation.

1.1. Hyoscine butylbromide (Buscopan) Because of its anticholinergic effects it is best avoided with other medicines that also have anticholinergic effects, for example, antihistamines, tricyclic antidepressants, and neuroleptics. It can be given during pregnancy and breastfeeding but avoided if possible. It should also be avoided in patients with glaucoma, myasthenia gravis and prostate enlargement.

1.2. Mebeverine Mebeverine is not known to interact with other medicines, has no cautions in its use and can be given in pregnancy and breastfeeding although there is a lack of detailed studies. It is associated with very few side effects although allergic reactions have been reported.

1.3. ALVERINE Like mebeverine, it is not known to interact with other medicines, has no cautions in its use and can be given in pregnancy and breastfeeding. It has no interactions with other medicines and can be used by all patient groups. Rash is the commonest side effect, although nausea, headache, dizziness, itching and allergic reactions have been reported.

1.4. PEPPERMINT OIL Adults and children aged over 15 can take peppermint oil. It often causes heartburn and rarely allergic rashes have been reported. It is safe to use in pregnancy but can decrease breast milk production. It has no drug interactions and can be used by all patient groups.

2. ALTERNATIVE TREATMENTS Probiotics, such as Lactobacillus and Bifidobacterium have also been promoted for IBS.