
Magnesium salicylate

Magnesium salicylate is a common analgesic and nonsteroidal anti-inflammatory drug (NSAID) used to treat mild to moderate muscular pain. It is also used to treat headaches, general back pain, and certain joint pains like arthritis.
It is found in a variety of over-the-counter (OTC) medications, most notably the brand of such medication called "Doan's Pills," as an anti-inflammatory, primarily for back-pain relief. Magnesium salicylate can be an effective OTC alternative to prescription NSAIDs, with both anti-inflammatory and pain-relieving effects.
Controversy.
While magnesium salicylate is an alternative for pain relief, it still is an NSAID like others in its category and can cause stomach ulcers, without any proven superiority over other 
over-the-counter type pain relievers (NSAID). 
Doan's specifically, and the company producing it, Novartis, have been tried over their claim that the product is superior in providing back pain relief. In June 1996, the FTC (Federal Trade Commission) charged the company with violating federal law with its unsubstantiated claim. In March 1998, the court ruled in favor of the FTC, but there was no stipulation about how the company should or would have to amend its advertising/packaging. Thus, Doan's was able to continue marketing as a "superior treatment for back pain".
In May 1999 the FTC released a statement summarizing the proceedings and announced the commission's decision after a 4–0 vote imposing a penalty on Doan's and its marketer, Novartis, to "run ads to correct misbeliefs resulting from their unsubstantiated claim that Doan's Pills are superior to other over-the-counter analgesics for treating back pain" and to modify packaging to include the statement "Although Doan's is an effective pain reliever, there is no evidence that Doan's is more effective than other pain relievers for back pain." The ads were required to run for a period of one year.