Class actions as well as individual legal actions involving medical or health products or services can arise in a wide variety of circumstances. Most well-known, of course, are actions against drug manufacturers for marketing an allegedly dangerous drug, like the cholesterol drug Baycol, the diabetes drug Rezulin, or the Fen-Phen diet drug combination. Similar actions can be filed against the firms who make allegedly dangerous medical devices, such as Sulzer's knee and hip implants, the St. Gobain Desmarquest artificial hip, or the silzone heart valves made by St. Jude Medical. Class actions have also been filed against the manufacturers of nutritional supplements, such as Metabolife and other products containing ephedra.

Some of these actions, whether based on drugs, medical devices, or nutritional supplements, contend, not that the product was always dangerous, but that the advertising for the product was misleading. Another type of class action that is becoming more common is one against a drug manufacturer claiming that the company has monopolized the drug so as to "fix" its price.

Another common type of legal action is one against the provider of medical services. Many such actions are filed for causing birth trauma to infants, or for other types of medical malpractice. Sometimes, such as in the case of actions against nursing homes, the alleged negligence may be by staff members other than doctors.