Medicine, Dhikr, Recovery And Their Relationship With Shirk
It is not shirk. Ayat-al-kursi is word of God, so any protection which comes from it’s recitation, is ultimately from God. While taking any medicine or reciting any dhikr, our belief should be that ultimate shifa lies with God only, these are just means which provide shifa to us in accordance with the law of cause and effect instituted by God in this world. One is a material cause (i.e. medicine) the other is a spiritual or nafsi cause (i.e. dhikr).