{"ok":true,"entry":{"slug":"verapamil","kind":"medication","name":"verapamil","aliases":["Isoptin"],"brands_sg":["Isoptin SR"],"class":"calcium channel blocker","tags":["heart-bp"],"use_for":"healthhub: irregular heartbeats and high blood pressure","use_after":"healthhub: with or without food; sr tablets swallowed whole","use_duration":null,"take_with":"water · healthhub: grapefruit raises the side-effect risk","pros":["nhs: it starts working on the day it is started","healthhub: relaxes and widens blood vessels","sg label: usually one 240 mg sr tablet in the morning"],"cons":["nhs: constipation is the most common side effect","healthhub: it can slow the heart rate further","healthhub: very rarely it can injure the liver"],"dose_note":"the singapore isoptin sr 240 mg label states the maximum outright: 'on long-term treatment a daily dose of 480mg should not be exceeded; short-term dose increases are possible only when directed by the physician'. the usual adult dose on that label is 'one film coated tablet in the morning', raised only 'if after about 2 weeks of treatment a dose increase is found to be necessary … to a maximum of 2 film coated tablets daily'. nhs quotes the same 480 mg a day ceiling for slow-release tablets in high blood pressure. isoptin sr 240 mg is the only verapamil product on the sg register.","dosage":null,"ul_status":null,"sg_class":"prescription-only","cautions":["heart failure, a very slow or irregular heart rate (nhs)","wolff-parkinson-white syndrome — nhs: may not be suitable","liver or kidney problems — sg label: dosage adjusted with care","myasthenia gravis, lems or duchenne md (nhs)"],"clashes":[{"src":["hh_ver_avoid","nhs_ver_about"],"food":true,"note":"healthhub: it may interact and increase the risk of side effects","with":"grapefruit"},{"src":["hh_ver_precautions"],"note":"healthhub: heart-rate slowing adds up; regular check-ups are advised","with":"beta blockers, digoxin or amiodarone"},{"src":["nhs_ver_int"],"note":"nhs: listed among medicines that may cause problems together","with":"simvastatin or atorvastatin"},{"src":["nhs_ver_int"],"note":"nhs: these can affect the way verapamil works","with":"clarithromycin, erythromycin, rifampicin or itraconazole"},{"src":["nhs_ver_int"],"note":"nhs: can affect the way verapamil works","with":"st john's wort"}],"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, cached in full and filtered locally)","quote":"Exactly one registered verapamil product: 'ISOPTIN SR TABLET 240 mg' [SIN00344P], Verapamil Hydrochloride, Forensic classification 'Prescription Only', ATC C08DA01, licence holder Abbott Laboratories (Singapore)","accessed":"2026-08-27"},{"id":"ndf_isoptin","url":"https://www.ndf.gov.sg/about-drugs/product-information/SIN00344P","label":"National Drug Formulary (SG, MOH) — ISOPTIN SR TABLET 240 MG [SIN00344P], approved indication and posology","quote":"the daily dose for adults is 1 film coated tablet in the morning … the dose can be raised to a maximum of 2 film coated tablets daily … a daily dose of 480mg should not be exceeded","accessed":"2026-08-27"},{"id":"hh_ver_uses","url":"https://www.healthhub.sg/medication-devices-and-treatment/medications/verapamil","label":"HealthHub (National Medication Information workgroup, SG) — Verapamil: what is this medication for","quote":"Verapamil is used to treat certain heart conditions such as irregular heartbeats. It can also be used to lower your blood pressure by relaxing and widening blood vessels.","accessed":"2026-08-27"},{"id":"hh_ver_howto","url":"https://www.healthhub.sg/medication-devices-and-treatment/medications/verapamil","label":"HealthHub — Verapamil: how should I take or use this medication","quote":"You may take this medication with or without food. If you are taking a sustained release tablet, you should swallow the tablet whole. Do not chew or crush sustained release forms of verapamil","accessed":"2026-08-27"},{"id":"hh_ver_precautions","url":"https://www.healthhub.sg/medication-devices-and-treatment/medications/verapamil","label":"HealthHub — Verapamil: what precautions should I take","quote":"This medicine can cause the heart rate to be slower and should be used with caution with other medicines that slow the heart rate e.g. digoxin, beta blockers and amiodarone.","accessed":"2026-08-27"},{"id":"hh_ver_side","url":"https://www.healthhub.sg/medication-devices-and-treatment/medications/verapamil","label":"HealthHub — Verapamil: common and rare but serious side effects","quote":"Leg swelling, headache and constipation … are some common side effects … This medicine may decrease your heart rate … Very rarely, this medicine can injure or damage the liver.","accessed":"2026-08-27"},{"id":"hh_ver_avoid","url":"https://www.healthhub.sg/medication-devices-and-treatment/medications/verapamil","label":"HealthHub — Verapamil: what food or medication should I avoid","quote":"Avoid taking grapefruit when you are taking this medicine as grapefruit may interact with your medicine and increase the risk of side effects.","accessed":"2026-08-27"},{"id":"nhs_ver_about","url":"https://www.nhs.uk/medicines/verapamil/about-verapamil/","label":"NHS — About verapamil, Key facts","quote":"Verapamil starts to work on the day you start taking it, but it may take 1 to 2 weeks to work fully. The most common side effect of verapamil is constipation. Do not eat grapefruit","accessed":"2026-08-27"},{"id":"nhs_ver_side","url":"https://www.nhs.uk/medicines/verapamil/side-effects-of-verapamil/","label":"NHS — Side effects of verapamil","quote":"Common side effects of verapamil … Constipation … Feeling or being sick … Flushing … Headaches","accessed":"2026-08-27"},{"id":"nhs_ver_who","url":"https://www.nhs.uk/medicines/verapamil/who-can-and-cannot-take-verapamil/","label":"NHS — Who can and cannot take verapamil","quote":"tell your doctor or pharmacist if you: … have low blood pressure … have any other heart problems, including heart failure, or a very slow or irregular heart rate have Wolff-Parkinson-White syndrome … myasthenia gravis","accessed":"2026-08-27"},{"id":"nhs_ver_int","url":"https://www.nhs.uk/medicines/verapamil/taking-verapamil-with-other-medicines-and-herbal-supplements/","label":"NHS — Taking verapamil with other medicines and herbal supplements","quote":"antibiotics, such as clarithromycin, erythromycin or rifampicin antifungal medicines, such as itraconazole digoxin or ivabradine … statins … such as simvastatin or atorvastatin … St John's wort … can affect the way verapamil works","accessed":"2026-08-27"},{"id":"nhs_ver_dose","url":"https://www.nhs.uk/medicines/verapamil/how-and-when-to-take-verapamil/","label":"NHS — Dosage and strength of verapamil","quote":"If you're taking slow-release tablets, the usual dose is 240mg, taken once a day. Your doctor may increase it to 480mg a day.","accessed":"2026-08-27"}],"brand_certs":null,"updated_at":"2026-08-29T16:16:34.039038+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."}