At the same time, Prof Kress stressed that the amounts prescribed should not be the sole consideration: "We must look at the increasing use of opioids from a number of different angles. Opioids are not without side effects, and for this reason they should only be prescribed in cases where patients do not have adverse reactions, where there are long-term benefits, and where other methods of treatment have failed." In addition to well-known side effects such as constipation, nausea and dry mouth, opioids can trigger a range of other reactions, the significance of which is often underestimated. They affect the hormonal system and metabolic processes. This was demonstrated in a Spanish study presented at the EFIC Congress (EFIC Abstract Ferri et al). More than 40% of the patients investigated complained of side effects such as nervousness and sexual dysfunction, and more than 30% suffered from insomnia ordepression. Another international study presented at the Congress suggested that many patients are given opioids where there are no clinical benefits
Also, see "Understanding Pain", at http://goo.gl/XpLH2S