Don’t believe me? there’s a lot of data to back up that claim.
The short version is, if you want your message to have an impact, don’t use more than two of them per social media message. Three or more and your message starts to become diluted, and your intended audience will ignore it. This is especially true on Twitter, though less so on other social networks like Instagram or Google Plus. On Facebook, hashtags are pretty much useless.
This is also worth keeping in mind if you’re posting the same content to multiple social networks. Don’t cram your content with hashtags on Twitter just because it’s going to Instagram, for example.
And of course, when using hashtags, make sure they’re relevant. Nothing will kill a message faster than its being tagged with an inappropriate hashtag, or tagged with something that happens to be trending or that has a lot of followers.
So the next time you want to strangle one of your friends for using too many hashtags, now you can do it politely, and explain that there are data to back you up.