Yes, emergency contraception can still be used on day 4 of your period after unprotected sex. It works best the sooner it's taken, ideally within 72 hours, though some options remain effective for a little longer.
Next Steps
Pregnancy risk is already lower during your period itself, but taking it soon still adds protection. It isn't meant for regular use, only as a backup.
Health Tips
At 44, cycles and fertility can be unpredictable, so if your next period is delayed or unusual, please see your gynaecologist for a check.