A catheter plug is a small cylinder-shaped piece of plastic that is inserted into the drainage tubing of the urinary bladder catheter, also called a Foley catheter. Inserting a catheter plug into the opening of the drainage tubing prevents urine from leaking out of the Foley catheter. The plug is used on occasions when the urine drainage bag may need to be removed, such as during bathing, showering, and some physical activities. Many catheter plugs feature ridges on the surface area of the plug that enable the patient to grasp it more securely for easier installation and removal of the small plastic piece. Some are packaged with a separate cover to protect the drainage tube and urine collection bag, while other plugs have a built in design that enables it to function as a plug or cover.

Most catheter plugs are designed to be used only once and are not able to be sterilized between uses. One type of catheter plug may be soaked in an isopropyl alcohol solution while the bladder is drained into the urine collection bag. Some catheter plugs may simply be wiped clean with isopropyl alcohol and re-inserted into the drainage tubing of the catheter during daily use. A catheter plug should never be used on more than one patient to avoid the risk of bacterial contamination from one patient to another.

The simplest catheter plug is a small latex-free plastic cone. It comes with a plastic cap that protects the shape of the plug when it is not in use. A cap may be used to cover the end of the connective tubing to the drainage bag when it is disconnected from the Foley catheter.

One plainly designed catheter plug is also cone-shaped. Small plastic ridges are located on the uppermost portion of the plug. It is individually packaged in a peel-back wrapping to enable the patient or caregiver to open it and plug the drainage tubing quickly.

Another type of catheter plug is shaped like a cone with a tapered end. The entire surface of this catheter plug is covered with ridges that enable the patient or caregiver to grasp the plug with ease. Raised areas on the plug also provide the user the ability to remove the plug with more control, which may relieve some of the momentary discomfort a person may feel as the plug is removed and the urine is allowed to drain from the bladder.