A shotgun is one of many names for a combination of over-the-counter pharmaceuticals. A shotgun is a combination of various ingredients, used to treat a variety of symptoms. The name may result from an analogy with an actual shotgun, which is used to hit a wide target area.

In general, most OTC products have more than one ingredient. Many of them have all of the major ingredients included. In general, there are about four main ingredients in OTC medicine:

Most of the products are different combinations of these four ingredients, with different dosages and different names.

Shotguns are in general a bad idea. The reason for this is clear: depending on the individual person's condition, they may have way more of one ingredient then they need. For example, a person with a runny nose may need more psuedoephedrine to clear up their congestion. It's quite possible to take 10 times the suggested dose of psuedoephedrine without causing (much) harm. If the product also includes tylenol, the person may accidentally end up overdosing on Tylenol. In addition, due to the fact that most substances are passed through the same metabolic pathway in the liver, a dose of a substance that may normally be tolerable can cause damage.

Instead of using shotgunned products, I personally would recommend buying each of the component products and using them as needed.