{"ok":true,"entry":{"slug":"levonorgestrel","kind":"medication","name":"levonorgestrel","aliases":["Postinor","Mirena"],"brands_sg":["Mirena","Postinor 2","Microgynon 30"],"class":"progestogen","tags":["hormonal"],"use_for":"contraception — daily pill, morning-after pill, or an ius","use_after":"nhs: the morning-after pill within 3 days (72 hours) of sex","use_duration":null,"take_with":"water for the tablets · the ius is fitted by a clinician","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"],"dose_note":"each singapore product carries its own label maximum. microgynon 30 (levonorgestrel with ethinylestradiol): 'One tablet is to be taken daily for 21 consecutive days. Each subsequent pack is started after a 7-day tablet-free interval'. mirena: 'It is effective for 8 years for contraception and for 5 years in the indication idiopathic menorrhagia' and 'The system should be removed or replaced after 8 years' (4 years when used for endometrial protection). for the emergency tablet, the national drug formulary publishes no posology for postinor 2 (0.75 mg × 2); the us plan b one-step label, a single 1.5 mg tablet, directs 'take as soon as possible within 72 hours (3 days) after unprotected sex'. the prescriber sets the product and the dose.","dosage":null,"ul_status":null,"sg_class":"prescription-only","cautions":["known or suspected pregnancy — contraindicated (sg mirena label)","current or recurrent pelvic inflammatory disease (sg mirena label)","acute or severe liver disease, or past stroke or heart attack (sg mirena label)","efavirenz, rifampin or seizure medicines may weaken it (us label)"],"clashes":[{"src":["fda_planb_warn"],"note":"us label: may reduce the effectiveness of levonorgestrel","with":"efavirenz (hiv medicine)"},{"src":["fda_planb_warn"],"note":"us label: may reduce the effectiveness of levonorgestrel","with":"rifampin (tuberculosis medicine)"},{"src":["fda_planb_warn"],"note":"us label: may reduce the effectiveness of levonorgestrel","with":"medicines for seizures (epilepsy)"}],"sources":[{"id":"hsa_register","url":"https://data.gov.sg/datasets/d_767279312753558cbf19d48344577084/view","label":"HSA — Listing of Registered Therapeutic Products (data.gov.sg open dataset, cached in full and filtered locally)","quote":"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","accessed":"2026-08-27"},{"id":"ndf_mirena_ind","url":"https://www.ndf.gov.sg/about-drugs/product-information/sin07915p/","label":"Singapore National Drug Formulary — MIRENA LEVONORGESTREL INTRAUTERINE SYSTEM [SIN07915P], section 4.1 indications","quote":"Contraception. Idiopathic menorrhagia … Protection from endometrial hyperplasia during oestrogen replacement therapy.","accessed":"2026-08-27"},{"id":"ndf_mirena_dose","url":"https://www.ndf.gov.sg/about-drugs/product-information/sin07915p/","label":"Singapore National Drug Formulary — MIRENA [SIN07915P], section 4.2 dosage and method of administration","quote":"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.","accessed":"2026-08-27"},{"id":"ndf_mirena_contra","url":"https://www.ndf.gov.sg/about-drugs/product-information/sin07915p/","label":"Singapore National Drug Formulary — MIRENA [SIN07915P], section 4.3 contraindications","quote":"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","accessed":"2026-08-27"},{"id":"ndf_microgynon_ind","url":"https://www.ndf.gov.sg/about-drugs/product-information/sin04834p/","label":"Singapore National Drug Formulary — MICROGYNON 30 TABLET [SIN04834P], section 4.1 indications","quote":"Oral Contraception.","accessed":"2026-08-27"},{"id":"ndf_microgynon_dose","url":"https://www.ndf.gov.sg/about-drugs/product-information/sin04834p/","label":"Singapore National Drug Formulary — MICROGYNON 30 TABLET [SIN04834P], section 4.2 dosage regimen","quote":"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.","accessed":"2026-08-27"},{"id":"fda_planb_use","url":"https://api.fda.gov/drug/label.json?search=openfda.brand_name:%22PLAN+B+ONE-STEP%22&limit=1","label":"US FDA OTC Drug Facts label for Plan B One-Step (levonorgestrel 1.5 mg), Use, via openFDA","quote":"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)","accessed":"2026-08-27"},{"id":"fda_planb_dir","url":"https://api.fda.gov/drug/label.json?search=openfda.brand_name:%22PLAN+B+ONE-STEP%22&limit=1","label":"US FDA OTC Drug Facts label for Plan B One-Step, Directions, via openFDA","quote":"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","accessed":"2026-08-27"},{"id":"fda_planb_warn","url":"https://api.fda.gov/drug/label.json?search=openfda.brand_name:%22PLAN+B+ONE-STEP%22&limit=1","label":"US FDA OTC Drug Facts label for Plan B One-Step, Warnings, via openFDA","quote":"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)","accessed":"2026-08-27"},{"id":"fda_planb_side","url":"https://api.fda.gov/drug/label.json?search=openfda.brand_name:%22PLAN+B+ONE-STEP%22&limit=1","label":"US FDA OTC Drug Facts label for Plan B One-Step, When using this product, via openFDA","quote":"When using this product you may have menstrual changes tiredness breast pain nausea headache vomiting lower stomach (abdominal) pain dizziness","accessed":"2026-08-27"},{"id":"nhs_ec","url":"https://www.nhs.uk/conditions/contraception/emergency-contraception/","label":"NHS — Emergency contraception","quote":"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.","accessed":"2026-08-27"}],"brand_certs":null,"updated_at":"2026-08-29T16:16:23.779398+08:00"},"disclaimer":"kozen-x is not a medical device and does not give medical advice. it lists what published sources have written down. absence of a record is not the same as safe."}