Breathlessness is a distressing and common symptom reported at the end of life. Opioids have been shown to improve the sensation of breathlessness,[15] and the doses used are generally smaller than those used for pain. The exact mechanism by which low dose opioids alleviate breathlessness is unknown, but is likely to be distinct from the mechanism by which inappropriately high doses of opioids cause respiratory depression. Studies have shown that opioid titration reduces respiratory rate and the sensation of dyspnoea, without substantial changes in PaO2 or PaCO2.[16] A systematic review of benzodiazepines for breathlessness in advanced disease showed a non-significant trend towards beneficial effect.[17] Nevertheless, for patients who are breathless and anxious, benzodiazepines can be useful.