What can I pour down a bath drain to dissolve hair and dust clumps?

[emanymton]

A big bottle of cheap supermarket own brand coke can work sometimes.

 

[petee]

Also, a plumber can come & snake the drain...

https://www.lowes.com/n/how-to/how-to-use-drain-snake

i invested in a proper one of those, not as good as the one in that picture, but still.
haven't had to use it yet, but i won't be surprised if the day comes.