Side effects are usually very few. Use may increase the risk of bacterial vaginosis and urinary tract infections. If left in the vagina for more than 24 hours toxic shock syndrome may occur. While use may decrease the risk of sexually transmitted infections, it is not very effective at doing so. There are a number of types of diaphragms with different rim and spring designs. They may be made from latex, silicone, or natural rubber. They work by blocking access to and holding spermicide near the cervix.