Diltiazem
Medication
calcium channel blocker
heart & blood pressure
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
HealthHub: irregular heartbeats; also lowers blood pressure
When to take
HealthHub: with or without food
Take with
HealthHub: grapefruit or its juice may raise side effects
Pros & cons
Pros
- HealthHub: taken with or without food
- SG label: usual adult dose 30 mg three times a day
- SG label: also indicated for variant angina pectoris
Cons
- HealthHub: leg swelling, headache, constipation
- HealthHub: dizziness on standing; slower heart rate
- HealthHub: very rarely, liver problems
Sources
- HSA — Listing of Registered Therapeutic Products (data.gov.sg open dataset, 5,511 rows, cached in full and filtered locally) · read 2026-08-27
what it says
“All 5 registered diltiazem products are HERBESSER and every row reads Forensicclassification 'Prescription Only' — SIN00428P HERBESSER TABLET 30 mg · SIN00430P HERBESSER 60 TABLET 60 mg · SIN06791P HERBESSER 90 SR CAPSULE · SIN10061P HERBESSER R200 CAPSULES 200 mg”
- HealthHub (National Medication Information workgroup, SG) — Diltiazem: what is this medication for · read 2026-08-27
what it says
“Diltiazem is used in the treatment of certain heart conditions such as irregular heartbeats. It may also be used to lower your blood pressure by relaxing and widening blood vessels.”
- HealthHub — Diltiazem: how should I take this medication · read 2026-08-27
what it says
“Do not stop taking your medication without checking with your healthcare professional. You may take this medication with or without food.”
- HealthHub — Diltiazem: common side effects · read 2026-08-27
what it says
“Some side effects may include: Leg swelling; Headache; Constipation (difficulty in passing stools); Dizziness and lightheadedness, especially when you get up from a lying or sitting position … Decreased heart rate”
- HealthHub — Diltiazem: rare but serious side effects · read 2026-08-27
what it says
“Very rarely, Diltiazem may cause liver problems … Liver injury - Dark brown urine, light coloured stools (pale grey/ clay coloured), nausea, vomiting, loss of appetite, yellowing of skin or eyes”
- HealthHub — Diltiazem: what food or medication should I avoid · read 2026-08-27
what it says
“Avoid taking grapefruit, or grapefruit juice as they may interact with your medication and increase the risk of side-effects.”
- HealthHub — Diltiazem: precautions (heart-rate-slowing medicines) · read 2026-08-27
what it says
“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.”
- Singapore National Drug Formulary (HSA/MOH) — HERBESSER 60 TABLET 60 MG [SIN00430P], Indications · read 2026-08-27
what it says
“INDICATIONS: Angina pectoris, variant angina pectoris; Essential hypertension (mild to moderate)”
- Singapore National Drug Formulary — HERBESSER 60 TABLET 60 MG [SIN00430P], Dosage and Administration · read 2026-08-27
what it says
“The usual adult dosage for oral use is 30 mg of diltiazem hydrochloride three times a day (90 mg/day). The dosage may be increased to 60 mg three times a day (180 mg/day), if necessary.”
- Singapore National Drug Formulary — HERBESSER 60 TABLET 60 MG [SIN00430P], Contraindications · read 2026-08-27
what it says
“Patients with severe congestive heart failure … Patients with 2nd- or 3rd-degree atrioventricular block or sick sinus syndrome … Pregnant women or women who may possibly be pregnant … Patients receiving ivabradine hydrochloride.”
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.