how long can i keep a bottle of opened calpol for?

[baybay]

Just wondering as there is no guideline on the bottle or box and no telephone number to contact them.
Can you keep it until the expiry date or is is recommended to be thrown out after a certain time period?
Luckily i have only had to use it a couple of times so the bottle is still almost full.

I think until the expiry date. What a con if you had to throw it away after a couple of doses.