Young women who were given the drops made from the liquorice-flavoured seeds felt less depressed and better equipped to go about their daily jobs and catch up with friends and family.
Health experts believe this is because fennel helps to rebalance the female sex hormones, which are to blame for some of the symptoms of PMT.
PMT affects three quarters of women, with extreme cases causing violent or depression to come on.
Many treat the symptoms with dietary changes, hormone boosters like the pill, or anti-depressants, but some of these drugs can have serious side effects.
Scientists in Iran who tested the fennel drops on women over an eight week period found that the “severity of symptoms had reduces so much that they could do their jobs and have a normal relationship with their friends and family.”
“Depression was also reduced,” they noted.
Study leader Dr. Hassan Pazoki from the Urmia University concluded that combining the fennel extract with regular exercise was the most effective way to combat the symptoms of PMT without any reported side effects.