The breakthrough has led to hope the therapy could eventually provide an alternative to expensive and risky Hormone Replacement Therapy for women of a certain age.
"This new analysis confirms the beneficial effect is obtained within just three days".
The study, an in-depth analysis of data collected from a clinical trial that was published a year ago, showed that the benefits can be seen incredibly quickly.
Scientists at Imperial College London have developed a new class of experimental drugs to treat menopausal hot flashes. They then switched to receive the other tablet for an additional four weeks.
In a clinical trial involving 37 women, the compound called MLE4901 reduced the number of hot flashes by nearly three-quarters and significantly reduced the severity. And many of them can find some, including hot flushes, debilitating.
MLE4901 can affect liver function but two similar drugs which don't have this side effect are being studied in larger patient trials including one in the US that was launched a year ago. However, two very similar drugs, which also block NKB but do not appear to carry these side effects have entered larger patient trials, with one such trial launched in the U.S. previous year.
Hot flushes usually occur as a result of change in your hormone levels.
For many women, these hot flushes may be little more than an uncomfortable inconvenience.
But a significant number suffer to such an extent that bed sheets end up drenched in sweat, while relentless insomnia can leave them struggling to cope during the day.
The new data also revealed that the drug was as effective at improving daytime flush symptoms as it was at improving night time symptoms.
Women reported a 82 per cent decrease in the amount their hot flushes interrupted their sleep and a 77 per cent reduction in interruption to their concentration.
Trials of MLE4901 on 39 women also saw a 72 per cent improvement in levels of sleep and a 67 per cent boost to concentration within days. To see the lives of our participants change so dramatically and so quickly was so exciting, and suggests great promise for the future of this type of treatment'.
Researchers said that it could offer a "much-needed alternative to HRT".