Has anyone taken this to delay periods for an event and then found it messed up their cycle afterwards? I took 10 days of Norethisterone in July for a holiday, then had a period after stopping. Took it for a couple of days in August for another trip and again had a period straight after stopping. My last period was on 1st September and I'm now 10 days late. I've done 5 negative pg tests, most recently on Sunday, but I've been feeling nauseous and tired. I'm wondering if i should see a doctor to be on the safe side, or whether it's just the Norethisterone messing things up a bit - it's not like me to be so late.