Unlike other tampons, which are made with cotton and rayon, Rely was unique. It used carboxymethylcellulose (CMC) and compressed beads of polyester for absorption. This tampon design could absorb nearly twenty times its own weight in fluid. Further, the tampon would "blossom" into a cup shape in the vagina in order to hold menstrual fluids. Because of this, its advertising slogan was "It even absorbs the worry!", and claimed it could hold up longer than the leading tampon, because it was made differently. "Remember, They named it Rely" was the last line of most commercials.
The superabsorbent properties of Rely caused vaginal dryness by absorbing the natural humidity of the vagina. Often this led to ulcerations in the vaginal wall when the tampon was removed, offering pathways for bacteria to infect the bloodstream. Further, the tampons' superabsorbency meant that the viscosity of vaginal fluids was enhanced, providing a good environment for bacteria growth. In addition, CMC has features which effectively filter the toxins of Staphylococcus which cause TSS
Procter and Gamble recalled Rely in September 1980 after the Centers for Disease Control released a report that summer, explaining the bacterial mechanism which lead to TSS, and that Rely tampons was associated with TSS more than any other tampon. As part of the voluntary recall, Procter and Gamble entered into a consent agreement with the Food & Drug Administration "providing for a program for notification to consumers and retrieval of the product from the market". The recall cost Procter and Gamble over 75 million dollars.