{"ok":true,"entry":{"slug":"levothyroxine","kind":"medication","name":"levothyroxine","aliases":["Euthyrox","Synthroid","T4"],"brands_sg":["Euthyrox","Eltroxin","Thyrocord","Rovexine","Thyrosit"],"class":"thyroid hormone","tags":["hormonal"],"use_for":"an underactive thyroid (hypothyroidism) — nhs, healthhub","use_after":"morning, once a day, at the same time each day","use_duration":null,"take_with":"an empty stomach, 30–60 min before food, coffee or medicines","pros":["nhs: can ease tiredness, weight gain and low mood","healthhub: generally well tolerated, side effects mild","nhs: usually one dose a day, taken long term"],"cons":["nhs: most side effects come from too high a dose","us label: boxed — not for obesity or weight loss","nhs: regular blood tests needed to check the dose"],"dose_note":"the us synthroid label (abbvie, spl v1537, eff. 20 feb 2024) states 'dosages greater than 200 mcg/day are seldom required' and that 'an inadequate response to daily dosages greater than 300 mcg/day is rare' — 300 mcg is also the highest tablet strength on that label. nhs gives no number at all: how much you need depends on thyroid hormone levels, other conditions and age, and the sg register lists tablets from 25 mcg to 100 mcg. the doctor sets the dose against blood tests.","dosage":null,"ul_status":null,"sg_class":"prescription-only","cautions":["overactive thyroid, adrenal or heart conditions (nhs)","diabetes (nhs) · angina or a past heart attack (healthhub)","pregnancy — nhs: can be taken, extra blood tests likely","biotin supplements — nhs: can distort thyroid test results"],"clashes":[{"src":["hh_levo_avoid","nhs_levo_inter"],"food":true,"note":"healthhub: 2–4 h before and after — absorption drops","with":"milk and dairy"},{"src":["hh_levo_avoid","nhs_levo_inter"],"note":"healthhub: 2–4 h before and after — absorption drops · nhs lists them too","with":"calcium and iron supplements"},{"src":["nhs_levo_inter","fda_synthroid_admin"],"note":"nhs: may not mix well · us label: 4 h apart from absorption-interfering drugs","with":"antacids, indigestion treatments and omeprazole"},{"src":["nhs_levo_inter"],"note":"nhs: can affect your thyroid tests, not the drug itself","with":"biotin (vitamin B7)"},{"src":["nhs_levo_inter"],"note":"nhs: listed among supplements that may not mix well","with":"st john's wort"},{"src":["nhs_levo_how"],"food":true,"note":"nhs: 30–60 min gap before the first caffeinated drink of the day","with":"caffeine — tea and coffee"}],"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, 5,511 rows, full CSV pulled once via the datastore_search API and filtered locally)","quote":"Forensicclassification = 'Prescription Only' for all 16 levothyroxine rows: EUTHYROX 25/50/75/100 mcg, Eltroxin 50/100 mcg, THYROCORD 25/50/75/100 MCG, ROVEXINE 25/50/75/100 MCG, THYROSIT TABLET 100 mcg, plus LEVOTHYROXINE SODIUM FOR INJECTION 500 mcg/vial","accessed":"2026-08-27"},{"id":"nhs_levo_about","url":"https://www.nhs.uk/medicines/levothyroxine/","label":"NHS Medicines A-Z — Levothyroxine: what it is used for (page dateModified 11 Aug 2026)","quote":"Levothyroxine is mainly used to treat an underactive thyroid (hypothyroidism). Levothyroxine can help with symptoms of an underactive thyroid including: tiredness · weight gain · low mood","accessed":"2026-08-27"},{"id":"nhs_levo_how","url":"https://www.nhs.uk/medicines/levothyroxine/","label":"NHS Medicines A-Z — Levothyroxine: how and when to take it","quote":"take it on an empty stomach 30 to 60 minutes before your first meal of the day, any drink with caffeine, such as tea or coffee, or any other medicine … You'll usually take it once a day.","accessed":"2026-08-27"},{"id":"nhs_levo_dose","url":"https://www.nhs.uk/medicines/levothyroxine/","label":"NHS Medicines A-Z — Levothyroxine: dosage","quote":"How much you need to take depends on your thyroid hormone levels, any other conditions you may have and your age … Your doctor may prescribe a low dose to start with and increase it gradually.","accessed":"2026-08-27"},{"id":"nhs_levo_side","url":"https://www.nhs.uk/medicines/levothyroxine/","label":"NHS Medicines A-Z — Levothyroxine: side effects","quote":"Common side effects of levothyroxine include: difficulty sleeping (insomnia) · headaches · feeling anxious · sweating · hair loss … Most side effects usually happen when the dose is too high.","accessed":"2026-08-27"},{"id":"nhs_levo_blood","url":"https://www.nhs.uk/medicines/levothyroxine/","label":"NHS Medicines A-Z — Levothyroxine: blood tests and monitoring","quote":"You'll have regular blood tests to check you're on the right dose of levothyroxine. Being on the wrong dose can cause side effects, such as feeling or being sick, diarrhoea, headaches or problems sleeping.","accessed":"2026-08-27"},{"id":"nhs_levo_who","url":"https://www.nhs.uk/medicines/levothyroxine/","label":"NHS Medicines A-Z — Levothyroxine: who can and cannot take it","quote":"levothyroxine is not suitable for everyone. For example, it may not be suitable if: you have an overactive thyroid · you have diabetes · you have a condition that affects your adrenal glands · you have a heart condition","accessed":"2026-08-27"},{"id":"nhs_levo_preg","url":"https://www.nhs.uk/medicines/levothyroxine/","label":"NHS Medicines A-Z — Levothyroxine: pregnancy and breastfeeding","quote":"Levothyroxine can be taken during pregnancy if needed. If you need to take levothyroxine while you're pregnant, you may need more blood tests to check your thyroid hormone levels and make sure you're taking the right dose.","accessed":"2026-08-27"},{"id":"nhs_levo_inter","url":"https://www.nhs.uk/medicines/levothyroxine/","label":"NHS Medicines A-Z — Levothyroxine: taking it with other medicines and herbal supplements","quote":"medicines to reduce the amount of acid in your stomach, such as omeprazole … antacids and other indigestion treatments · calcium and iron supplements … St John's wort · biotin (vitamin B7) as it can affect your thyroid tests","accessed":"2026-08-27"},{"id":"hh_levothyroxine","url":"https://www.healthhub.sg/medication-devices-and-treatment/medications/levothyroxine","label":"HealthHub (MOH Singapore / Pharmaceutical Society of Singapore) — Levothyroxine medication information leaflet, last reviewed 21 May 2026","quote":"Take Levothyroxine in the morning on an empty stomach, at least 30 minutes before the first food or drink of the day … Do not stop taking your medication or change the brand of levothyroxine without informing your doctor.","accessed":"2026-08-27"},{"id":"hh_levo_avoid","url":"https://www.healthhub.sg/medication-devices-and-treatment/medications/levothyroxine","label":"HealthHub — Levothyroxine leaflet: food and medicines to avoid, tolerability","quote":"Avoid food, drinks, medications or supplements that are high in calcium, iron or magnesium 2 to 4 hours before and after taking Levothyroxine … Generally, this medication has been well tolerated. Side effects usually have been mild","accessed":"2026-08-27"},{"id":"fda_synthroid","url":"https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=1e11ad30-1041-4520-10b0-8f9d30d30fcc","label":"FDA DailyMed — SYNTHROID (levothyroxine sodium) tablets, AbbVie Inc., SPL v1537, effective 20 Feb 2024: dosing footnote","quote":"Dosages greater than 200 mcg/day are seldom required. An inadequate response to daily dosages greater than 300 mcg/day is rare and may indicate poor compliance, malabsorption, drug interactions, or a combination of these factors","accessed":"2026-08-27"},{"id":"fda_synthroid_boxed","url":"https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=1e11ad30-1041-4520-10b0-8f9d30d30fcc","label":"FDA DailyMed — SYNTHROID prescribing information: boxed warning","quote":"WARNING: NOT FOR TREATMENT OF OBESITY OR FOR WEIGHT LOSS — Thyroid hormones, including SYNTHROID, either alone or with other therapeutic agents, should not be used for the treatment of obesity or for weight loss.","accessed":"2026-08-27"},{"id":"fda_synthroid_admin","url":"https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=1e11ad30-1041-4520-10b0-8f9d30d30fcc","label":"FDA DailyMed — SYNTHROID prescribing information: section 2.1 Important Administration Instructions","quote":"Administer SYNTHROID as a single daily dose, on an empty stomach, one-half to one hour before breakfast. Administer SYNTHROID at least 4 hours before or after drugs known to interfere with SYNTHROID absorption","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."}