Doctor

Riddle: You go to the doctor because you're ill and he prescribes you with 3 pills and tells you to take them every half hour. How long do the pills last you?

Answer: An hour because the first pill doesn't take 30 min. to take.

Source: https://www.riddles.com/1358

You go to the doctor because you're ill and he prescribes you with 3 pills and tells you to take them every half hour.
How long do the pills last you? — Doctor by Anonymous v1.

Riddle: You go to the doctor because you're ill and he prescribes you with 3 pills and tells you to take them every half hour.
How long do the pills last you? Answer: An hour because the first pill doesn't take 30 min. to take. — by Anonymous v2.