It isn’t as straightforward as that. You need to look at the causes of these absences and if there is any pattern to them.
What you may need to do is rethink your company policy in respect of paying for sickness absence above and beyond statutory sick pay or limit the entitlement.
Find out the causes for the sickness and see if there is an underlying reason behind them. Look at your capability procedure and see if you have a trigger point relating to absence at which point you will start taking employees through the capability procedure for absences that aren’t disability related.
Carry out a return to work interview with your employee after each absence to look at the reason for it. You can warn your employee that her absence is becoming unacceptably high and that if it doesn’t improve she will be put through the formal procedures.