What are the side effects of nifedipine (calcium channel blocker)?

Side Effects of Nifedipine

The most common side effect of nifedipine is peripheral edema, which is dose-related and occurs in 18-29% of patients, followed by vasodilatory symptoms including headache, dizziness, flushing, and palpitations due to its potent action on vascular smooth muscle. 1, 2

Common Side Effects

Cardiovascular Effects

• Peripheral edema: Dose-dependent (18% at 30mg daily, 29% at 90mg daily) 1
• Vasodilatory symptoms:
  • Headache
  • Dizziness/lightheadedness
  • Flushing
  • Palpitations
  • Hypotension (especially orthostatic)
• Reflex tachycardia: Due to peripheral vasodilation 2

Gastrointestinal Effects

• Nausea
• Constipation (less common with nifedipine than with verapamil) 3
• Rarely: diarrhea 4

Dermatologic Effects

• Rash
• Rarely: urticaria, exfoliative dermatitis, Stevens-Johnson syndrome, toxic epidermal necrolysis 1

Less Common Side Effects

Neurological Effects

• Paresthesia
• Vertigo
• Rarely: tremor, sleep disturbances, mood changes, nervousness 1

Musculoskeletal Effects

• Leg cramps
• Arthralgia 1

Urogenital Effects

• Erectile dysfunction
• Urinary frequency
• Nocturia 1

Rare but Serious Side Effects

• Cardiovascular: Severe hypotension, especially when used with beta-blockers without proper monitoring 5
• Hepatic: Allergenic hepatitis, jaundice 1
• Hematologic: Anemia, leukopenia, thrombocytopenia 1
• Immunologic: Anaphylactic reactions 1

Special Considerations

Contraindications

• Severe left ventricular dysfunction: Nifedipine has less negative inotropic effect than verapamil or diltiazem but should still be avoided in patients with significantly impaired left ventricular function 2
• Immediate-release nifedipine: Not recommended for unstable angina/NSTEMI except with concomitant beta blockade due to increased adverse potential 5

Drug Interactions

• Beta-blockers: Can be used safely with nifedipine but require monitoring for additive hypotensive effects 2
• Digoxin: Nifedipine may increase serum digoxin levels, though clinical significance is uncertain 3
• Magnesium sulfate: Combination may increase risk of uncontrolled hypotension 5

Metabolic Effects

• High doses may inhibit insulin release, which should be considered in diabetic patients 3

Management of Side Effects

1. For peripheral edema:

   • Consider combining with ACE inhibitors to reduce risk 2
   • Elevate legs when sitting
   • Reduce dose if possible

2. For vasodilatory symptoms:

   • Monitor blood pressure in both sitting and standing positions 2
   • Consider slow titration of dose
   • Switch to extended-release formulation if using immediate-release

3. For severe side effects:

   • Discontinue medication and consider alternative calcium channel blockers (e.g., amlodipine, which may have better tolerability in some patients) 2

Important Precautions

• Immediate-release nifedipine should be avoided without concomitant beta blockade in unstable angina/NSTEMI 5
• Monitor elderly patients more closely for orthostatic hypotension and peripheral edema 2
• Start with lower doses in elderly patients 2
• Check electrolytes and renal function periodically, especially if combined with diuretics 2

Nifedipine's side effect profile differs from non-dihydropyridine calcium channel blockers (verapamil, diltiazem) which have more pronounced negative chronotropic and dromotropic effects on the heart 2.