I wouldn't call it the wonder drug for IBS. Some drugs help some people and some don't.
"Effect of Low-Dose Naltrexone for IBS
Naltrexone* is an opioid antagonist that blocks excitatory but not inhibitory opioid receptors. It has been speculated that an alteration in the opioid system may play a pathophysiologic role underlying the abdominal pain and other symptoms in IBS.
The efficacy of PTI-901 (low-dose naltrexone at 0.5 mg orally daily for 4 weeks) was evaluated for the treatment of IBS in 37 patients positive by Rome II criteria (23 women and 14 men; mean age 48.5 years) in an open-label study. An improvement in global assessment score occurred in 76% of patients. The average weekly pain-free days increased from 0.4 to 1.24 (P = .05). No drug-related adverse events were reported. These results are very preliminary, but suggest that naltrexone may have a beneficial effect on IBS. Large, randomized, double-blind, placebo-controlled trials are needed.
The opioid antagonist naltrexone is a novel, potentially therapeutic agent for the treatment of IBS. In a preliminary, open-label study, this agent was demonstrated to improve global assessment and abdominal pain in patients with IBS. However, further studies are needed to establish its effectiveness in IBS.
* The United States Food and Drug Administration has not approved this medication for this use.
These were studies done back in 2003. They were small studies and some of it I believe didn't pan out exactly as they had hoped for in IBS.
However it could be worth asking your doctor about.
You can search pubmed and see what studies there are for it.
I am not a doctor. All information I present is for educational purposes only and should not be subsituted for the advise of a qualified health care provider.
Please make sure you have your symptoms diagnosed by a medical practitioner or a doctor.