Period-delay tablets work by keeping your hormone levels steady, so the uterine lining doesn't shed on schedule. The most commonly prescribed option is norethisterone (sold as Primolut-N and similar brands) — but it only works if you start it before your period would normally begin, and your period is expected within a few days of stopping it, so timing both ends matters as much as taking the tablet itself.
When to start
Norethisterone needs to be started a few days before your expected period — not after it's already begun. Your doctor will usually have you start it around three days before your period is due, timed against your own cycle, so this is a "plan ahead" medicine rather than one you can reach for once bleeding has already started. If your cycle is irregular, this timing becomes harder to predict on your own, which is exactly why it's worth a quick consult rather than guessing from an app's prediction.
How long you can keep taking it
The tablet is taken continuously, usually two to three times a day, for as long as you want your period delayed — commonly used for stretches of a few days up to around two weeks for a trip or event. It isn't intended for indefinite, repeated use as a routine way of skipping periods month after month without your doctor's involvement.
When to stop, and what happens after
Once you stop taking it, your period typically arrives within two to three days as hormone levels drop and the lining sheds. Some irregularity in timing or flow in that first cycle after stopping is common and isn't by itself a sign that something went wrong — your next cycle after that one is usually back to its usual pattern.
The tablet doesn't prevent your period — it postpones it until you choose to stop taking it. Both the start date and the stop date need to be planned against your own cycle, not estimated.
Before you take it
- Confirm the dose and timing with your doctor based on your actual cycle length and when your period is due, rather than copying a friend's regimen
- It is not a contraceptive. Norethisterone delays your period; it does not prevent pregnancy, so continue using your usual contraception if that's relevant to you
- Flag any history of blood clots, liver disease, migraine with aura, or breast cancer before starting, since norethisterone may not be suitable in these situations
- Don't use it repeatedly, cycle after cycle, as a routine way to control period timing — it's meant for occasional, planned use around a specific event
Frequently asked
Can I start the tablet after my period has already begun?
No — norethisterone needs to be started before your period starts in order to delay it. Once bleeding has begun, the tablet won't stop or postpone that cycle's period.
How many days before my period should I start?
This is typically around three days before the period is due, but the right starting point depends on your own cycle and is best confirmed with your doctor rather than estimated from a general rule.
Will my period come immediately after I stop the tablet?
Usually within two to three days of stopping, though the exact timing can vary slightly by person. Some spotting or irregularity in that first cycle is common and generally resolves on its own by the next one.
Is it safe to use this every month to control when my period comes?
It's intended for occasional, planned delays — not as a monthly routine. Repeated use without a specific reason is worth discussing with your doctor, since it isn't the right tool for ongoing period management the way hormonal contraception can be.
What if I need emergency contraception while I'm already taking the delay tablet?
That's a different situation with its own timing questions — see combining a period-delay pill with emergency contraception rather than deciding on your own.