Final answer:
Determining the possibility of drug allergies is the highest priority when obtaining information about a patient's medications in an emergency situation.
Step-by-step explanation:
When a patient comes into the ER barely conscious, the highest priority in obtaining information about his medications would be to determine the possibility of drug allergies. Knowing the patient's allergies is crucial to avoid administering medications that could potentially worsen the patient's condition or cause an allergic reaction. This information is especially important in emergency situations where immediate treatment is necessary.