For a long time, it has been the conventional wisdom that hashtags tend to improve the reach and interaction rate of social media posts.
However, a recent report by Socialbakers suggests that brands shouldn't overdo it. Like with so many other things in live, it's the dosage that makes the poison. According to Socialbakers, the average number of interactions generated by brands' Facebook posts drops when more than two hashtags are included.
You will find more statistics at Statista