There are two types of personal lubricants and personal gels.

Water based are easily washed from the body, come in various flavors, can warm (or even cool) during use and will help maintain the strength of a condom. 

Silicone based lubricants contain no water, require soap and water to be removed and can lead to the ripping or destruction of a condom. They do not, however dry up, so they last longer than water based gels  or lubricants. There are no known major medical  studies on the use of either silicone or water based personal gels or personal lubricants. Two studies did suggest, that parabens, a product used  in making water based lubricants and gels can cause allergic reactions. Most manufacturers list the ingredients used in making gels or lubricants. The most popular brands on the market are the various K-Y Lubricants.