You're asking whether spotting on Day 16 while taking Primolut‑N (norethisterone 5 mg) from Day 3–21 is okay.

⚕️ What this likely is

• This is most likely breakthrough or withdrawal spotting from taking norethisterone; spotting can occur while the body adjusts to progestogen and is common mid‑cycle when on short courses.
• Because you started Primolut‑N on Day 3 and are still within the prescribed course (up to Day 21), this pattern is often expected and usually not dangerous.

💊 What to do now

• Continue the tablets exactly as your doctor prescribed unless they advised otherwise.
• Use sanitary protection and track bleeding amount and timing (note Day 16 and any changes).
• If you missed doses, restart as advised by your prescriber — do not stop suddenly without checking.
• See your gynecologist if you feel uncertain or want a medication review.

⚠️ When to see a doctor

• Heavy bleeding (for example, soaking through a pad every hour) or sudden large clots.
• Severe pain, fainting, fever, or feeling very unwell.
• Signs of deep vein thrombosis (DVT) such as new calf swelling/redness, sudden breathlessness, or chest pain.

🩺 FOLLOW_UP

• Did you miss any doses since Day 3?
• Are you pregnant or is there a possibility of pregnancy, and are you taking any other medications or supplements?

If you want, I can explain why norethisterone causes spotting or what to record for your gynecologist.