The guidance - which also applies to sponsored links on search engines - clarifies the agency’s position on platforms with character limits.
The FDA says firms tweeting benefit claims “should also incorporate risk information within the same character-space-limited communication.”
Drug tweets “should also provide a mechanism to allow direct access to a more complete discussion of the risks associated with its product.”
The document was published with more general guidance to help pharmas avoid disseminating misinformation on drugs on social media platforms.
Unlike the latest agency guidance, the earlier documents discussed drug industry use of online banners and pages on networks like Facebook.
The FDA said such media “platforms do not impose the same character space constraints as online microblog messaging and online paid search.”
Previous agency efforts to regulate the promotional use of the internet have already been subjected to considerable drug industry criticism.
In April Pfizer said the FDA “does not have any general authority to regulate promotion” beyond what constitutes “labelling or advertising.”
Whether the new draft guidance receives similar criticism from drugmakers keen to stress the benefits of their medicines remains to be seen.
What is clear, as observant readers will note, is that even without including lists of potential risks sticking to 140 characters is tricky.