Every 4 hours, in short
Every 4 hours (written q4h on prescriptions) means 6 doses in 24 hours, spaced evenly around the clock, including overnight. A common every 4 hours schedule is 8am, 12pm, 4pm, 8pm, 12am and 4am.
Every 4 hours schedules
With an 8-hour night, at least one every 4 hours dose always falls while you're asleep. Starting at your wake-up time keeps it to one. For someone who sleeps from 11pm to 7am:
| Schedule | Doses during an 11pm to 7am night |
|---|---|
| 7am, 11am, 3pm, 7pm, 11pm, 3am | 1 (3am) |
| 8am, 12pm, 4pm, 8pm, 12am, 4am | 2 (12am and 4am) |
| 6am, 10am, 2pm, 6pm, 10pm, 2am | 2 (2am and 6am) |
Planning every 4 hours around sleep
Many every 4 hours prescriptions, especially for pain relief, are written as needed (PRN). That usually means no more often than every 4 hours, rather than on a fixed clock. If yours isn't marked PRN and you're not sure about the night doses, ask your pharmacist.
How many doses in a course?
| Course length | Doses (1 every 4 hours) |
|---|---|
| 5 days | 30 |
| 7 days | 42 |
| 10 days | 60 |
| 14 days | 84 |
The total is the same whatever time of day you start. Your pharmacist can confirm how many doses your prescription should have.
Common questions
How many times a day is every 4 hours?
Every 4 hours is 6 times a day, because 24 hours divided by 4 is 6 doses. A typical schedule is 8am, 12pm, 4pm, 8pm, 12am and 4am.
Do you take every 4 hours medicine overnight?
It depends on how it's prescribed. Medicines written as needed (PRN) every 4 hours are usually taken only when you need them, no more often than every 4 hours. A fixed every 4 hours schedule includes night doses, so ask your pharmacist if you're not sure which yours is.
How many doses is every 4 hours for 5 days?
30 doses, which is 6 a day for 5 days. A 7 day course is 42 doses.