My 7 year old daughter has a cough which goes and comes but she has had it for a couple of months now...when she coughs i give her a little cough mixt?

Immdiate exam: Your daughter should be examined as soon as possible at a medical clinic. It is possible your daughter has a lingering bacterial infection which can be treated with antibiotics. If her cough appears to be due to a lingering viral infection more aggressive supportive care would be indicated. And if instead her cough appears to be from allergies she should be treated for her allergies.

How disruptive ?: If this does not interfere with her daily activities it is likely minor. A discussion with her doc at her next encounter would help sort out the cause. If it has interfered with her enjoyment of play or caused a change in scheduled activities it should be seen sooner rather than later.