How do you calculate what's Day 1 of your period if you've been taking the pill back-to-back for months ?

[Melbob]

Been taking the pill back-to-back to treat Endo and now need to know Day 1 of my cycle. Stupid question but is it the first day of a new pill pack or do you calculate it based on cycle length from when you first started taking the pill? I'm a bit confused!

[Impatient]

Day 1 is the 1st day you see blood from a period.

Starting to take the Pill should commence on that 1st day, so pill 1 is on day 1.

If you are on the combi pill which is 3 weeks of live tablets and then 1 week of sugar tablets, when you take them back to back you cut out the sugar ones and switch to a 21 days live tablets followed by the next 21 days and so on. Each time you start a new packet becomes day 1.

This applies if each of the live tablets contains the same ingredients.

But there are BC Pills which are phased doses to be taken in strict order. 7 days one colour, then 7 days a different colour and so on. These are called Triphasic pills.

With these it is sometimes better to start on a particular day of the week after your period has started - for example change colours on a monday each week, keeping track of the order in which you are taking them.

Day 1 becomes your chosen day for starting taking the pill of the first colour rather than your first day of a period. Again these can be taken back to back with the next start day of the new packet becoming Day 1 again.

So for both methods Day 1 is the start of the new pack, and you are on a 3 week or 21 day pill cycle.

Forget your actual period due date from before you started the pills. If you were regular as clockwork, then sometimes you note in a diary every 28 days or 26 or whatever your regular cycle is, so you know roughly when the next period is due. But you need to ignore that when you are on the pill.

There are some drugs like Norethisterone where there isn't a Day1 as such.

you just take your pills daily until such time as you are ready for a period then stop taking them and a couple of days later AF begins. Then once that has stopped you take them again before you ovulate and carry on as before until such time as you are ready for the next period. you don't need to waste taking them while you are having a period, so have a week off them if you want to, while you bleed, then restart them.

I hope that answers your question.

[Aeb123 in reply to Impatient]

Hi there, sorry I know this is 3 years ago now but I found your answer very helpful. I am just wondering as I am on the pill rigevidon where I have 3 weeks of the same dosage taking the pill and 1 week of no pills which is when I have my withdrawl bleed. I am just trying to understand my cycle better in terms of my hormones and relating this to my gym/exercise routine. Do you know when would be the first day of my cycle? Is it the first day I stop taking the pills or the first day I start a new pack or the first day of my withdrawl bleed? Any info would be much appreciated. Thanks

[Melbob]

Thanks so much that's great. I just needed to know for a blood test before starting IVF. As my periods have always been all over the place I really struggled to track them properly. This really helps , thank you