How long does Tylenol with codeine stay in your body?

It depends on the individual's body type (i.e., height, weight, overall condition, etc), the brand of cough syrup, the given dosage, and the amount of codeine in that dosage; the age of the medication and the environment (i.e., temperature, humidity, etc) are also factors. Therefore, there is no set answer for this question. As such, always follow the manufacturer's, pharmacist's, and/or doctor's recommendations for the given medications.