Frog in Your Throat was a popular brand of throat lozenges at the turn of the century. They printed a number of cards like this one around 1905 that generally featured a lovely lady in the foreground and a leering frog in the background. The lozenges contained licorice, coltsfoot, wild cherry bark, horehound, cubeb, capsicum, menthol, potassium bitartrate, peppermint, sugar, and other aromatics. Here's a link to a website that shows a nice collection of Frog in Your Throat ephemera.
The back of the card is nice too. It's labeled as a Private Mailing Card instead of a postcard. Prior to the congressional act in 1898, the US Government had a monopoly on printing postcards. After 1898, private mailing cards were allowed, but until 1907 only the address and no message was allowed on the back of the card. That means that a lot of these cards are mysterious; unless the sender wrote on the picture side, there's little indication of who sent it.
While we don't know who sent the card, we do know that it was sent to Miss Prudence Davis of Portland, Maine. A short search revealed that Prudence Augusta Davis (of the same address) studied at Smith College and married Melville H. Marston on Thursday, November 6, 1913.