diltiazem hydrochloride at a glance
Medicine class
Rate-limiting calcium-channel blocker
Main licensed uses
Angina and, for several selected products, mild to moderate hypertension
Formulation matters
Release profiles differ; continue the prescribed brand unless reviewed
Administration
Swallow modified- or prolonged-release products whole with water; do not crush or chew
What is diltiazem hydrochloride used for?
Selected oral products cover these licensed indications:
Prevention and treatment of angina pectoris; some products specify stable angina.
Mild to moderate hypertension for selected prolonged-release products.
Raynaud’s phenomenon and topical treatment of anal fissure are non-licensed contexts outside the selected oral product licences.
How does diltiazem hydrochloride work?
Diltiazem limits calcium entry into vascular smooth muscle and heart muscle. It widens coronary and systemic arteries, lowers vascular resistance and cardiac workload, and can slow sinoatrial and atrioventricular conduction.
diltiazem hydrochloride preparations and strengths
Capsule
Route: Oral
Strengths: 90 mg, 120 mg, 180 mg, 200 mg, 240 mg, 300 mg
Modified-release capsule
Route: Oral
Strengths: 120 mg, 180 mg, 200 mg, 240 mg, 300 mg
How to take diltiazem hydrochloride
Follow the dispensing label and keep to the prescribed brand and formulation. Food instructions vary by product, so check the pack leaflet.
Swallow modified- or prolonged-release tablets or capsules whole with water; do not crush or chew them.
Ask a pharmacist or prescriber before changing brand or formulation, or if swallowing is difficult.
Do not stop treatment without discussing it with the prescriber.
diltiazem hydrochloride side effects
Common or expected effects
- Swollen ankles, feet or hands
- Headache
- Dizziness or light-headedness
- Flushing
- Constipation, indigestion, nausea or abdominal discomfort
- Tiredness, weakness or general malaise
- Palpitations
Get urgent medical advice
- Fainting, marked slowing of the heartbeat or symptoms of heart block
- New or worsening heart failure, including severe breathlessness or rapidly increasing swelling
- Bronchospasm or worsening asthma symptoms
- Yellow skin or eyes, dark urine or severe abdominal pain suggesting liver injury
- Severe blistering, peeling or widespread skin reactions
- Face, mouth or throat swelling, breathing difficulty or collapse
diltiazem hydrochloride in pregnancy
Diltiazem is not usually recommended during pregnancy, and product restrictions differ. Evidence has not identified clear risks from calcium-channel blockers overall, but experience with diltiazem is limited. Do not stop it without review; hypertension, angina or rhythm problems may require obstetric and cardiology assessment.
diltiazem hydrochloride while breastfeeding
Selected product licences contraindicate breastfeeding, but current UK specialist advice says milk transfer appears negligible and cautious use may be considered after individual assessment. An alternative may be preferred. Monitor the infant for unusual sleepiness, pallor, poor feeding or inadequate weight gain.
diltiazem hydrochloride interactions
Diltiazem affects cardiac conduction and inhibits CYP3A4 and P-glycoprotein, so a full medicines review is important.
Ivabradine
Contraindicated because combined heart-rate lowering can cause clinically important bradycardia.
Common questions about diltiazem hydrochloride
Answers are fully visible for fast scanning and source review.
Why should diltiazem hydrochloride usually stay on the same brand?
Modified- and prolonged-release brands can release it differently. A switch may alter exposure and clinical response, so it should be reviewed.
Can modified- or prolonged-release products be crushed?
Sources
These sources were used to prepare and review this medicine page.
Prepared and reviewed by the iatroX editorial team.