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Phosphodiesterase-3 Inhibitor (Antiplatelet/Vasodilator) Pregnancy: Cilostazol must not be used during pregnancy (contraindicated). There are no adequate data in pregnant women and animal studies have shown reproductive toxicity; the potential risk for humans is unknown. Use is not recommended during breast feeding because of the potential harmful effect in the newborn child.

Cilostazol

Brand names: Pletal

Cilostazol is a phosphodiesterase type 3 inhibitor used as a second-line option to improve walking distance in people with intermittent claudication who have no rest pain or tissue necrosis.

Auto-extracted from the source labelling — not yet independently clinician-verified. These values were distilled from the UK SPC (or the US label where noted) but have not had a clinician sign-off. Confirm against the current SmPC before prescribing.

Adult dose

Dose: 100 mg twice a day
Route: Oral (fetched product: cilostazol 100 mg tablets)
Frequency: Twice daily, taken 30 minutes before breakfast and the evening meal
Max: Maximum 100 mg per dose, twice a day - the fetched UK SPC states only 'The recommended dosage of cilostazol is 100 mg twice a day' and gives no higher dose; the dose must be reduced (not increased) to 50 mg twice daily with strong CYP3A4 or CYP2C19 inhibitors.
Should be initiated by physicians experienced in the management of intermittent claudication. 'The physician should reassess the patient after 3 months of treatment with a view to discontinuing cilostazol where an inadequate effect is observed or symptoms have not been improved.' DOSE REDUCTION: 'Reduction of the dose to 50 mg twice daily is recommended in patients receiving medicines that strongly inhibit CYP3A4, for example some macrolides, azole antifungals, protease inhibitors, or medicines that strongly inhibit CYP2C19, for example omeprazole.' Taking cilostazol with food increases the maximum plasma concentration and may be associated with an increased frequency of adverse reactions. Patients should continue lifestyle modification (smoking cessation, exercise) and pharmacological interventions such as lipid lowering and antiplatelet treatment - cilostazol is not a substitute for these. No special dosage requirements in older people. HEPATIC: no dose adjustment in mild hepatic disease; contraindicated in moderate or severe hepatic impairment. SURGERY: if elective surgery is planned and antiplatelet effect is not necessary, stop cilostazol 5 days before surgery (eMC 4.4). PAEDIATRIC: 'The safety and efficacy of cilostazol in children have not been established.' US cross-check: same 100 mg twice daily, taken at least half an hour before or two hours after breakfast and dinner; 'If symptoms are unimproved after 3 months, discontinue cilostazol.' eMC sections 4.4 and 4.8 were truncated at the source-fetch limit.

Dose adjustments

Renal

No dose adjustment is necessary in patients with a creatinine clearance of more than 25 ml/min. Cilostazol is contraindicated in patients with a creatinine clearance of 25 ml/min or less.

Dose auto-extracted from UK Summary of Product Characteristics (SPC) via the eMC; US FDA prescribing information (openFDA / DailyMed) — cross-check; US labelling may differ from UK — not yet clinician-verified. Always confirm against the product SmPC and your local formulary before prescribing.

Contraindications

  • Hypersensitivity to the active substance or to any of the excipients
  • Severe renal impairment: creatinine clearance of 25 ml/min or less
  • Moderate or severe hepatic impairment
  • Congestive heart failure
  • Pregnancy
  • Any known predisposition to bleeding (e.g. active peptic ulceration, haemorrhagic stroke within the past six months, proliferative diabetic retinopathy, poorly controlled hypertension)
  • Any history of ventricular tachycardia, ventricular fibrillation or multifocal ventricular ectopics, whether or not adequately treated, and prolongation of the QTc interval
  • History of severe tachyarrhythmia
  • Concomitant treatment with two or more additional antiplatelet or anticoagulant agents (e.g. acetylsalicylic acid, clopidogrel, heparin, warfarin, acenocoumarol, dabigatran, rivaroxaban or apixaban)
  • Unstable angina pectoris, myocardial infarction within the last 6 months, or a coronary intervention in the last 6 months
  • US labelling adds: heart failure of any severity (boxed warning - phosphodiesterase III inhibitors have decreased survival in class III-IV heart failure)

Side effects

  • Headache (reported in more than 30% in clinical trials; the only adverse event causing discontinuation in 3% or more of patients)
  • Diarrhoea and abnormal stools (more than 15% each)
  • Palpitation, tachycardia, angina pectoris, arrhythmia, ventricular extrasystoles
  • Oedema (peripheral, face), dizziness, rhinitis, pharyngitis
  • Nausea and vomiting, dyspepsia, flatulence, abdominal pain
  • Ecchymosis and bleeding at various sites (eye haemorrhage, epistaxis, gastrointestinal haemorrhage); rare or very rare haematological abnormalities - thrombocytopenia, leucopenia, agranulocytosis, pancytopenia and aplastic anaemia, some fatal

Interactions

  • Strong CYP3A4 inhibitors (e.g. some macrolides, azole antifungals, protease inhibitors) - plasma levels of cilostazol are increased; reduce the dose to 50 mg twice daily
  • Strong CYP2C19 inhibitors (e.g. omeprazole) - plasma levels increased; reduce the dose to 50 mg twice daily
  • US labelling additionally names diltiazem, erythromycin, ketoconazole, itraconazole, ticlopidine, fluconazole and grapefruit juice among the CYP3A4/CYP2C19 inhibitors requiring the 50 mg twice daily dose
  • Two or more additional antiplatelet or anticoagulant agents - contraindicated; cilostazol itself carries an increased bleeding risk which may be potentiated by any other agent with such potential
  • Other agents that lower blood pressure - possible additive hypotensive effect with reflex tachycardia
  • Vasodilators that cause reflex tachycardia (e.g. dihydropyridine calcium channel blockers) - increased frequency of palpitation and peripheral oedema

Monitoring

  • Reassess the patient after 3 months of treatment with a view to discontinuing cilostazol if the effect is inadequate or symptoms have not improved (eMC 4.2)
  • Full blood count if infection is suspected or there is any other clinical evidence of blood dyscrasia; discontinue promptly if there is clinical or laboratory evidence of haematological abnormality
  • Warn patients to report any episode of bleeding or easy bruising, and any pyrexia or sore throat suggesting early blood dyscrasia; stop cilostazol in the case of retinal bleeding
  • Close monitoring of patients at increased risk of serious cardiac adverse events from an increased heart rate (e.g. stable coronary disease) - cilostazol raises heart rate by approximately 5 to 7 bpm
  • US labelling adds: monitor platelet and white blood cell counts, and monitor for a new systolic murmur or cardiac symptoms after starting cilostazol (left ventricular outflow tract obstruction)

Clinical monograph

How it works

By inhibiting phosphodiesterase III it raises intracellular cyclic AMP, producing vasodilatation and inhibition of platelet aggregation, which improves peripheral blood flow.

Prescribing in practice

  • Cilostazol is contraindicated in heart failure of any severity because other phosphodiesterase III inhibitors increase mortality in this group.
  • It is metabolised by CYP3A4 and CYP2C19, so doses are reduced with potent inhibitors such as certain macrolides, azoles and omeprazole.
  • Avoid in those with predisposition to bleeding and review combined use with antiplatelets or anticoagulants.

Monitoring

Review symptomatic benefit on walking distance after the early weeks of treatment and stop if there is no worthwhile improvement, while watching for palpitations and bleeding.

Counselling the patient

  • Take it on an empty stomach, before food in the morning and evening.
  • Headache, palpitations and diarrhoea are common early on and often settle.
  • Stop and seek advice if you develop breathlessness or ankle swelling.

Evidence & guidelines

NICE recommends cilostazol as an option for claudication based on trials showing modest improvements in pain-free and maximal walking distance versus placebo.

Reference: NICE NG97 PAD guidelines; CASTLE trial; Drug verified in RxNorm (NLM); confirm dosing against the manufacturer SPC (eMC). Verify against your local formulary and current prescribing references before prescribing. The structured dose values shown have been reviewed by a clinician. Monograph status: clinician-reviewed (2026-07-04).

Related

Curated clinical cross-links plus same-class fallbacks.

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