Calcium channel blockers (DHP, -dipine) — patient guide

This page covers all the medicines in the dihydropyridine calcium channel blocker family. If your medicine’s name ends in -dipine, this is your page.

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Find your medicine

Generic name	Common brand names	Strengths	How often
Amlodipine	Norvasc, generics, Coveram (with perindopril), Exforge (with valsartan), Caduet (with atorvastatin)	2.5 / 5 / 10 mg	Once daily
Felodipine	Plendil, generics	2.5 / 5 / 10 mg	Once daily (extended release)
Nifedipine (controlled release)	Adalat Oros, generics	30 / 60 mg	Once daily
Lercanidipine	Zanidip, generics	10 / 20 mg	Once daily (on empty stomach)
Nimodipine	Nimotop	30 mg	Specialist hospital use only — every 4 hours

Nimodipine is not a hypertension medicine. It’s used by neurosurgeons after a particular kind of brain bleed (subarachnoid haemorrhage) to prevent blood-vessel spasm. If you’ve been prescribed nimodipine for high blood pressure, please query that — it should be one of the others in the table.

Felodipine — modified-release tablets must be swallowed whole. Don’t crush, split, or chew. Crushing releases the entire day’s dose at once and causes a steep BP drop.

Lercanidipine — take on an empty stomach, at least 15 minutes before food. A fatty meal can multiply absorption substantially.

Closely related family — ACE inhibitors and ARBs. Names end in -pril (ACE inhibitors) or -sartan (ARBs). Often co-prescribed with a -dipine in the same combination tablet (Coveram, Exforge, Twynsta, Sevikar — see the combinations section below).

Different family with the same name — non-DHP CCBs. Verapamil and diltiazem are calcium channel blockers too, but they work mainly on the heart rather than the arteries. Different side effects, different cautions — they live on a separate page (coming).

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What it treats

DHP calcium channel blockers are prescribed for:

• High blood pressure — the most common reason. Often combined with an ACE inhibitor or ARB.
• Stable angina — to reduce the frequency of chest tightness on exertion by relaxing the coronary arteries and reducing the heart’s workload.
• Raynaud’s phenomenon — off-label use, particularly for amlodipine, where the cold-induced finger spasm is bothersome enough to want a daily medicine.
• After a particular kind of brain bleed (subarachnoid haemorrhage) — nimodipine only, specialist hospital use, to prevent blood-vessel spasm.

The mechanism is the same across all of these — relaxing the smooth muscle in the arteries. The reason matters because in stable angina the drug is doing both BP-lowering and direct coronary-vessel work, and we don’t usually stop it just because BP is well-controlled.

I’ll tell you which situation you’re in.

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The basics

1. Take it at the same time every day. All the routine DHP CCBs are once daily. Miss a dose? Take the next one — don’t double up. Amlodipine in particular has a long half-life (35–50 hours), so a missed dose by half a day is rarely consequential.
2. Watch for ankle swelling. Common, dose-related, not heart failure — but tell us if it bothers you.
3. Be careful with grapefruit — felodipine especially. See the food section below.
4. Don’t stop on your own. If something feels wrong, message me — we can almost always fix the problem without stopping the medicine.

Everything else — side effects, what to track, the integrative angle — is below.

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What to expect in the first month

Week 1

• You may notice flushing, mild headache, or feeling warm — vasodilatory effects, usually settling inside 1–2 weeks.
• You probably won’t feel the BP coming down. Most people don’t.
• Light-headedness on standing in the first few days is normal — get up slowly.

Weeks 2–4

• The full BP effect builds over 1–2 weeks (a touch longer for amlodipine because of its long half-life).
• Ankle swelling, if it’s going to happen, usually shows up here. It’s dose-related — at 5 mg amlodipine roughly 1 in 20 people notice it; at 10 mg closer to 1 in 10.
• We’ll meet to review your home BP readings.

Pause-and-call situations

DHP CCBs don’t usually need the strict “sick day rules” pause that ACE inhibitors and diuretics need — they’re more tolerant of dehydration. But message us if:

• You develop sudden, significant ankle/face swelling.
• You feel persistently light-headed or have a fainting episode.
• You notice your heart racing or pounding (rare with the modern long-acting forms, more an issue with the now-avoided short-acting nifedipine capsules).
• You’re hospitalised for any reason — make sure the admitting team knows you’re on it.

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Tap any section below to expand the detail.

How does it work?

DHP calcium channel blockers block the L-type calcium channels in vascular smooth muscle. Smooth muscle needs calcium to flow into the cell to contract — without that calcium signal, the muscle relaxes. The arteries relax, the resistance the heart pumps against drops, and BP comes down.

The “DHP” (dihydropyridine) part of the name describes the chemical structure, which is what makes this family selective for blood vessels rather than the heart itself. That’s why these drugs don’t slow the heart rate (unlike verapamil and diltiazem, the non-DHP siblings).

The same vasodilatation explains the side-effect profile: ankle swelling (small arteries relax more than small veins, fluid leaks into the tissues), flushing (skin vessels relax), and gum overgrowth (the mechanism is still debated but seems to relate to the calcium channel’s role in gum-tissue cell turnover).

Side effects in detail

Common (usually mild)

• Ankle swelling (peripheral oedema). Roughly 1 in 10 people, dose-related, more common with amlodipine and felodipine at higher doses, often less with lercanidipine. Not heart failure — the fluid is leaking into the tissues because the small arteries relax more than the small veins. Water tablets don’t help much; the fix is dose reduction or a switch.
• Flushing, warmth, mild headache — vasodilatory effects, especially in the first 1–2 weeks. Usually settles.
• Light-headedness on standing, especially in the first few days. Stand up slowly. Stay hydrated.
• Gum overgrowth (gingival hyperplasia). Long-term use, modifiable by good oral hygiene and regular dental cleans, but not always fully prevented.

Uncommon

• Palpitations / awareness of heartbeat — rare with the modern long-acting forms. The historical reason short-acting nifedipine capsules are now avoided is they caused reflex tachycardia by dropping BP too fast.
• Constipation (more typical of the non-DHP CCBs verapamil and diltiazem, but can happen with the DHPs too).
• Sleep disturbance, mild fatigue.

Rare but serious — get medical attention

• Severe hypotension — particularly when felodipine is combined with grapefruit (the CYP3A4 interaction can multiply blood levels several-fold per TGA PI Norvasc). Light-headedness, near-fainting, or actual fainting after a meal containing grapefruit needs ED review.
• Worsening of pre-existing heart failure — most of the older DHP CCBs are not safe in heart failure with reduced ejection fraction. Only amlodipine and felodipine have evidence supporting safety in compensated HFrEF (PRAISE, V-HeFT III).
• Allergic reaction — rash, swelling, breathing difficulty. Rare; needs ED.

Drugs, food, and alcohol

Tell me or your pharmacist before combining with:

• Grapefruit and grapefruit juice — the big one. Inhibits CYP3A4 in the gut wall. Felodipine: avoid entirely. Amlodipine: avoid regular daily intake. Pomelo and Seville orange have the same effect. Ordinary orange, lemon, lime, and mandarin do not.
• Other CYP3A4 inhibitors — clarithromycin, erythromycin, itraconazole, ketoconazole, ritonavir. Raise DHP CCB levels; combination may need dose adjustment or a different antibiotic/antifungal.
• Simvastatin — amlodipine raises simvastatin levels. The Australian recommendation is to cap simvastatin at 20 mg when on amlodipine. Atorvastatin and rosuvastatin don’t have the same issue. (Caduet — amlodipine + atorvastatin — uses atorvastatin partly for this reason.)
• CYP3A4 inducers — carbamazepine, phenytoin, rifampicin, St John’s wort. Drop DHP CCB levels; BP may drift up.
• Other BP-lowering agents — common and intentional in combination tablets, but the dose-stacking is what gives the BP effect; don’t add on your own without us knowing.
• Sildenafil / tadalafil / vardenafil (for erectile dysfunction) — can stack with the BP-lowering effect. Usually still safe; tell us so we can advise.

Food. No specific restrictions other than grapefruit. Lercanidipine is the exception — take on an empty stomach, at least 15 minutes before food, because a fatty meal substantially increases absorption.

Alcohol. Light to moderate amounts are okay. Heavy drinking worsens the vasodilatory side effects (flushing, light-headedness) and destabilises BP control.

Generic substitution at the pharmacy. Generic amlodipine, felodipine, nifedipine CR, and lercanidipine are bioequivalent — they work the same. The one thing worth checking is that a controlled-release nifedipine generic is indeed labelled controlled-release / extended-release / Adalat-Oros-equivalent — the short-acting form (now uncommon) is not interchangeable.

Monitoring — what blood tests and when

DHP CCBs are kinder to the kidneys than ACE inhibitors and don’t need the same close blood-monitoring schedule. Routine checks are:

• BP check 2–4 weeks after starting or after a dose change.
• Annual kidney function and electrolytes as part of your routine cardiovascular review.
• Dental review at least yearly, more often if you notice gum changes — particularly on long-term DHP CCBs.
• Message us if you: develop ankle swelling that bothers you, start a new medicine (including over-the-counter or supplements), become pregnant or plan a pregnancy, or feel persistently dizzy.

Stopping or pausing

Don’t stop without talking to me first.

• If side effects are the problem, we usually swap medicines rather than stop. Within the family, switching to lercanidipine for ankle swelling is a common move. Outside the family, the alternatives are an ACE inhibitor, an ARB, or a thiazide diuretic.
• DHP CCBs don’t typically need the strict sick-day pause that ACE inhibitors and diuretics need — they’re more tolerant of dehydration. Still, if you’re unwell and not eating or drinking properly for more than 24–48 hours, message us.
• Before surgery, your anaesthetist may or may not ask you to hold a dose. Follow their instructions — most often DHP CCBs are continued through the perioperative period.
• Stopping cold turkey can let BP rebound. If the medicine is also treating angina, stopping suddenly can let the angina come back.

Pregnancy and breastfeeding

This is more nuanced than for ACE inhibitors. Some DHP CCBs are actively used in pregnancy under specialist supervision; others have limited data.

• Nifedipine (controlled release) has the most pregnancy data and is used by obstetricians for high blood pressure in pregnancy, including pre-eclampsia. This is a specialist-managed indication — not something to assume applies to other DHP CCBs or to start on your own.
• Amlodipine is increasingly used in pregnancy where the benefit outweighs the risk, but each case is reviewed.
• Felodipine, lercanidipine — limited pregnancy safety data; usually switched to a better-studied agent (often labetalol, methyldopa, or nifedipine CR) under obstetric supervision.

If you’re planning a pregnancy, tell me at the planning stage — we can review which medicine you’re on and plan any switch in advance.

If you’ve just found out you’re pregnant, contact me as soon as possible. Don’t stop the medicine on your own — uncontrolled high BP in pregnancy is its own risk. We just choose the safest option for you and the baby together.

Breastfeeding. Amlodipine and nifedipine are detectable in breast milk but at very low levels and are generally considered compatible with breastfeeding. We’ll choose case by case.

If you’re on a combination tablet

Many DHP CCBs come pre-combined with another BP-lowering drug or a statin. If your tablet name is one of these, you’re on more than just a -dipine:

• Coveram = perindopril + amlodipine
• Triplixam = perindopril + indapamide + amlodipine
• Exforge = valsartan + amlodipine
• Exforge HCT = valsartan + amlodipine + hydrochlorothiazide
• Sevikar = olmesartan + amlodipine
• Sevikar HCT = olmesartan + amlodipine + hydrochlorothiazide
• Twynsta = telmisartan + amlodipine
• Caduet = amlodipine + atorvastatin (the statin is for cholesterol; the amlodipine is for BP)

Everything on this page applies to the amlodipine portion of your combination. The other drug has its own side effects and considerations — the ACE inhibitor page covers perindopril; the ARB and thiazide pages will follow.

Cost

All the routine DHP CCBs are on the PBS. From 1 January 2026, the PBS co-payment is:

• General patient: up to $25.00 per script
• Concession card holder: up to $7.70 per script

Generic amlodipine, felodipine, nifedipine CR, and lercanidipine cost the same as the branded versions at PBS pricing and work the same. Confirm with your pharmacist — they can show you the exact price for your script and tell you the cheapest equivalent.

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The integrative view

Most of the patients I see want to do everything they reasonably can in addition to the medicine. This section is the longer version of that conversation.

Two principles. First: DHP CCBs work and they’re well-evidenced (ALLHAT, ASCOT-BPLA, VALUE). Lifestyle changes also work. Combined, they work better than either alone. Second: medicines aren’t always permanent. For BP, if you genuinely change your habits, your dose may come down or come off — but we do that together, with monitoring, not on your own.

Strong evidence — these reliably lower BP

These are interventions where the data is solid enough that I’d recommend them to any patient on a -dipine for BP. Effect sizes are in mmHg systolic so you can see the magnitude.

• DASH-style eating pattern (NEJM 1997). Vegetables, fruit, whole grains, lean protein, low saturated fat, low added sodium. Expected effect: ~6–11 mmHg systolic.
• Sodium reduction below 2 g/day (~5 g salt). Most sodium is hidden in processed food, not the saltshaker. Effect: 5–6 mmHg, more if you’re salt-sensitive.
• Aerobic exercise. 150 minutes/week of brisk walking, cycling, swimming. Effect: 5–7 mmHg.
• Resistance training. 2–3 sessions/week. Adds another 2–4 mmHg on top of aerobic.
• Weight loss. Roughly 1 mmHg per kg lost, sustained.
• Reducing alcohol. Each standard drink per day above 1–2 adds 1–2 mmHg of BP. Cutting back: 3–4 mmHg of room to work with.
• Treating sleep apnoea if you have it. Effects vary; can be large. Snoring + daytime tiredness + observed pauses in breathing is worth a sleep study.

Moderate evidence — likely helpful

• Magnesium-rich foods (leafy greens, nuts, seeds, legumes, dark chocolate). Particularly relevant for this drug class — magnesium acts as a physiological calcium-channel modulator at the vascular smooth-muscle level, so adequate intake supports what the medicine is doing. Food first; supplements only if there’s a specific reason.
• Stress reduction practices — meditation, slow breathing (~6 breaths/minute), yoga. 2–5 mmHg over months of practice.
• Hibiscus tea, 2–3 cups daily. Several studies show 3–7 mmHg systolic reduction. Roughly equivalent to a small dose of medicine.
• Dietary nitrate — beetroot juice, leafy greens (spinach, rocket). 4–5 mmHg.

Limited or emerging evidence

• Fish oil, high dose (3+ g EPA/DHA daily). 2–4 mmHg. The bigger reason to take it is broader cardiovascular protection.
• CoQ10 — mixed evidence for BP itself. More relevant if you’re also on a statin.
• Aged garlic, L-theanine, hawthorn — weak evidence. Not recommendations I’d make on the data alone; I won’t talk you out of them if they’re already part of your routine. Tell us about aged garlic before starting if you’re on blood thinners — it can affect bleeding.

Specific to being on a DHP CCB

• Grapefruit. Already covered above — felodipine entirely, amlodipine in moderation. The takeaway: substitute another citrus, your morning juice doesn’t have to disappear.
• Magnesium adequacy. As noted — magnesium and calcium-channel modulation share biology. Adequate dietary magnesium is a sensible target. Symptoms of low magnesium include muscle cramps, restless legs, palpitations — mention them and we can decide whether to check a level.
• Ankle swelling — practical management. If it’s bothering you and you don’t want to switch yet: compression stockings (15–20 mmHg, knee-high) reduce visible swelling significantly. Leg elevation for 15 minutes a couple of times a day helps. A diuretic doesn’t (this isn’t fluid overload — it’s tissue leak from vasodilatation), and adding one risks dropping BP too far.
• Dental hygiene matters more on this class than on others. Twice-daily brushing, daily flossing, six-monthly cleans. Tell your dentist which medicine you’re on.

Off-label — amlodipine for Raynaud’s

Cold, white, painful fingers in winter — Raynaud’s phenomenon — is the other main reason an integrative GP might use amlodipine. The Cochrane review (Ennis 2016) shows a modest reduction in attack frequency and severity versus placebo, and the Australian Rheumatology Association endorses DHP CCBs as a first-line pharmacological option when non-drug measures (hand-warming, smoking cessation, avoiding cold exposure, beta-blocker review) haven’t been enough.

This is off-label use — it’s not the licensed indication. That means the decision is more individual: how much it’s bothering you, what you’ve already tried, whether the trade-off of a daily medicine is worth it for you. That’s the conversation we have in the consult.

Earning a lower dose

DHP CCBs aren’t permanent for everyone. If you genuinely change your eating, movement, weight, and alcohol intake, your BP may drop enough that we can reduce the dose — sometimes off entirely. This is a goal worth aiming for.

Two caveats:

• We do this together, with regular home BP monitoring. Not on your own.
• If you’re on the -dipine for stable angina rather than BP, we usually keep it going regardless of BP, because the drug is doing more than treating a number. I’ll tell you which group you’re in.

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Track these between now and your next visit

• Home BP readings — daily for the first 2 weeks, then a couple of times a week. Same time of day.
• Ankle swelling — present? Bothering you? At what time of day worst?
• Any new symptoms — flushing, headache, gum changes, palpitations — note when they started and how often.
• Anything new you’ve bought over the counter (painkillers, supplements, grapefruit-containing things).

Bring the list to your review appointment.

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This is general information, not personal medical advice. Every patient is different. Decisions about your medicines — which one, what dose, when to stop, what to combine with — are made with the doctor who prescribed them. If anything on this page appears to contradict advice from your treating doctor, follow your doctor; they have context about your situation that this page cannot.

Reading this page does not establish a doctor-patient relationship with Dr Hoebing Lo. If you are not a current patient, please discuss your medicines with your own GP, specialist, or pharmacist.

About the integrative content. The lifestyle, dietary, and complementary recommendations on this page summarise current published research. Effect sizes are approximations from clinical studies — your individual response will vary, and real-world results are commonly smaller than trial results because day-to-day life differs from study conditions. Supplements and herbal products are not interchangeable with prescribed medication and can interact with it. Talk to your doctor and pharmacist before starting any new supplement, herbal product, or significant change in diet.

About off-label use. The Raynaud’s use of amlodipine described in the integrative section is off-label — not the licensed indication. It is supported by Cochrane evidence and Australian Rheumatology Association guidance, but the decision is individual and made in the consult, not from a webpage.

Currency. This page reflects clinical practice as of the last-reviewed date. Medicine evolves; specific details may date between reviews. Pricing shown is indicative; confirm with your pharmacist.

No commercial relationships. Dr Hoebing Lo has no financial or commercial relationship with the manufacturer of any medicine, brand, or supplement mentioned on this page.

Emergencies. If you have sudden severe swelling, difficulty breathing, chest pain, fainting, or a fall after a meal containing grapefruit, call 000 or go to your nearest emergency department. Do not wait, and do not message us first.