It grants +3 to your charisma but lowers your intelligence and perception by 3.
However, there is a unmarked quest in Rivet City.
Talk to Angela Staley. She wants you to get her Ant Queen Pheromones. When you give it to her, it will take a few days until Angela seduces Diego, the acolyte in the Rivet City church. This quest simply grants Good Karma if you attend the wedding.
There are only FOUR Pheromones in the entire Capital Wasteland. (One sold by Cindy Cantelli, 3 can be obtained by killing the Ant Queens in Marigold Metro Station (Part of Those! quest, so be careful if you haven't completed it.), one in north of Shalebridge and one in Corvega Factory.)