Breakthrough bleeding like this, where flow gets heavier partway through a pack on Femilon, usually happens when hormone levels dip through the cycle or after a missed or delayed pill. It's a common pattern on hormonal contraception and is generally not dangerous, though it can be frustrating to deal with.
Next Steps
Please don't combine or switch between Primolut N, Crina NCR and Femilon or Crimson 35 on your own. The right combination and dose depends on your cycle history, so see your gynaecologist in person so they can confirm what's safe for you.
Health Tips
Get checked urgently if a pad soaks through within an hour, you pass large clots, or you feel dizzy or very weak.