Which of the following medications requires a prescription in Canada?

The correct answer is hydrocodone, which requires a prescription in Canada. Hydrocodone is an opioid analgesic that is used for the treatment of severe pain. Due to its potential for abuse, dependency, and serious side effects, legislation in Canada classifies hydrocodone as a controlled substance, mandating that it can only be dispensed with a valid prescription from a licensed healthcare provider.

In contrast, levonorgestrel is available over-the-counter in Canada and is used primarily for emergency contraception. Vitamin K, also not requiring a prescription, is essential for blood clotting and can be obtained in various dietary supplements and formulations without a doctor's order. Benzoyl peroxide is commonly used for treating acne and is found in many over-the-counter skincare products, reflecting its safety profile for general public use without requiring a prescription.