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Levonorgestrel

Medication progestogen hormonal
Aka: Postinor, Mirena
Brands seen in Singapore: Mirena, Postinor 2, Microgynon 30
Not medical advice. Check with your doctor or pharmacist before you start, stop or change the timing of anything you take.
How to use
What it’s for
Contraception — daily pill, morning-after pill, or an ius
When to take
NHS: the morning-after pill within 3 days (72 hours) of sex
Take with
Water for the tablets · the ius is fitted by a clinician
Pros & cons
Pros
  • SG label: mirena covers 8 years of contraception
  • NHS: the sooner the emergency pill, the better it works
  • US label: the emergency dose is a single 1.5 mg tablet
Cons
  • HSA register: all 3 SG products are prescription-only
  • US label: not for regular birth control
  • US label: menstrual changes, nausea, headache
Sources
  1. HSA — Listing of Registered Therapeutic Products (data.gov.sg open dataset, cached in full and filtered locally) · read 2026-08-27
    what it says
    “Only 3 levonorgestrel products are registered, all with Forensicclassification 'Prescription Only' — SIN07915P MIRENA LEVONORGESTREL INTRAUTERINE SYSTEM 20 mcg/24 hr · SIN11836P POSTINOR 2 TABLET 0.75 mg · SIN04834P MICROGYNON 30 TABLET”
  2. Singapore National Drug Formulary — MIRENA LEVONORGESTREL INTRAUTERINE SYSTEM [SIN07915P], section 4.1 indications · read 2026-08-27
    what it says
    “Contraception. Idiopathic menorrhagia … Protection from endometrial hyperplasia during oestrogen replacement therapy.”
  3. Singapore National Drug Formulary — MIRENA [SIN07915P], section 4.2 dosage and method of administration · read 2026-08-27
    what it says
    “Mirena is inserted into the uterine cavity. It is effective for 8 years for contraception and for 5 years in the indication idiopathic menorrhagia … The system should be removed or replaced after 8 years.”
  4. Singapore National Drug Formulary — MIRENA [SIN07915P], section 4.3 contraindications · read 2026-08-27
    what it says
    “Known or suspected pregnancy · Current or recurrent pelvic inflammatory disease · Active or previous severe arterial disease, such as stroke or myocardial infarction · Liver tumour or other acute or severe liver disease”
  5. Singapore National Drug Formulary — MICROGYNON 30 TABLET [SIN04834P], section 4.1 indications · read 2026-08-27
    what it says
    “Oral Contraception.”
  6. Singapore National Drug Formulary — MICROGYNON 30 TABLET [SIN04834P], section 4.2 dosage regimen · read 2026-08-27
    what it says
    “One tablet is to be taken daily for 21 consecutive days. Each subsequent pack is started after a 7-day tablet-free interval, during which time a withdrawal bleed usually occurs.”
  7. US FDA OTC Drug Facts label for Plan B One-Step (levonorgestrel 1.5 mg), Use, via openFDA · read 2026-08-27
    what it says
    “Active ingredient Levonorgestrel 1.5 mg … Purpose Emergency contraceptive … Use for women to reduce chance of pregnancy after unprotected sex (if a contraceptive failed or if you did not use birth control)”
  8. US FDA OTC Drug Facts label for Plan B One-Step, Directions, via openFDA · read 2026-08-27
    what it says
    “take as soon as possible within 72 hours (3 days) after unprotected sex. The sooner you take it the better it will work. if you vomit within 2 hours after taking the medication, call a healthcare professional”
  9. US FDA OTC Drug Facts label for Plan B One-Step, Warnings, via openFDA · read 2026-08-27
    what it says
    “Do not use if you are already pregnant (because it will not work) for regular birth control … if you are taking efavirenz (HIV medication) or rifampin (tuberculosis treatment) or medication for seizures (epilepsy)”
  10. US FDA OTC Drug Facts label for Plan B One-Step, When using this product, via openFDA · read 2026-08-27
    what it says
    “When using this product you may have menstrual changes tiredness breast pain nausea headache vomiting lower stomach (abdominal) pain dizziness”
  11. NHS — Emergency contraception · read 2026-08-27
    what it says
    “levonorgestrel (brands include Levonelle) which you need to take within 3 days (72 hours) after sex … The sooner you use emergency contraception, the more effective it usually is.”
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Updated 2026-08-29. Every line above traces to a numbered source. Kozen-X is not a medical device and does not give medical advice. It lists what published sources have written down — nothing more. A pair not listed is unrecorded, not cleared. Before you start, stop or re-time anything, talk to your doctor or pharmacist.