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Mosquito repellent liquids can cause allergic cold, and cough in some kids. I cannot say definitely if that is the cause of cold and cough in your kid. But in this season, many kids are suffering from viral respiratory tract infections. So the cause may be a viral infection or allergic cold due to other reasons like cold weather, dust, rain, etc.
If you have been using the repellent for a long time and she has not suffered from frequent cold, cough then that may not be the cause. Better take her to the doctor so that cause can be identified. If you have any follow up queries please be clear about the age and weight of your child which are not tallying.