Arret Loperamide 2mg Capsules (6). This medicine is used to treat sudden shortlived (acute) attacks of diarrhoea in adults and children aged 12 years and over.. The capsules contain loperamide hydrochloride which helps reduce diarrhoea by slowing down an overactive bowel, which helps the body to absorb water and salts from the bowel.. ARRET™ Capsules should be used in conjunction with oral rehydration therapy which replaces fluids and salts lost during diarrhoea.