WASHINGTON, DC: A number of major pharma firms, including Johnson & Johnson and GlaxoSmithKline, have received a warning letter from the US Food and Drug Administration regarding their online search ads, which are said to contain insufficient information about the risks of taking certain drugs.

The FDA contacted a total of 14 pharma companies, and was concerned about search ads for 48 brands, 19 of which had received a "black box" rating, indicating they have the highest risk of side effects.

The corporations involved include Bayer, Novartis, Merck & Co., Eli Lilly, Pfizer and Roche, all of which were informed that their "sponsored links" appearing when consumers searched for a brand or illness must contain any relevant safety information.

Biogen also received a letter from the FDA relating to its multiple sclerosis drug Tysabri, which said the company's search ads exhibited a "casual approach" given the "potentially lethal risks of the drug and the stringent controls over its distribution."

Sanofi-Aventis was also warned that the links for its anti-clotting product Plavix, one of the world's biggest-selling pharma brands, "misleadingly suggest Plavix is safer than has been demonstrated."

The FDA also contacted Pfizer about a total of six different brands, including its anti-smoking aid Chantix and arthritis drug Celebrex.

Data sourced from Wall Street Journal; additional content by WARC staff