Cilostazol is a prescription medication used to treat intermittent claudication, the cramping leg pain that occurs during walking when narrowed arteries restrict blood flow to the legs. It is the only FDA-approved drug specifically indicated to increase walking distance in people with this condition. Sold under the brand name Pletal, cilostazol works by improving blood flow and preventing blood clots in the affected arteries.
Intermittent Claudication: The Core Use
Peripheral artery disease (PAD) causes fatty deposits to build up inside the arteries that supply your legs. When those arteries narrow enough, your muscles can’t get sufficient oxygen during activity. The result is a predictable pattern: you walk a certain distance, pain or cramping sets in (usually in the calves), and you’re forced to stop. Once you rest, the pain fades. That cycle is intermittent claudication, and it’s what cilostazol targets.
The drug doesn’t reverse the artery narrowing itself. Instead, it relaxes blood vessel walls and makes platelets (the blood cells responsible for clotting) less sticky, which together improve circulation through compromised arteries. This lets you walk farther before pain forces you to stop.
How Well It Works
In a large randomized trial published in JAMA Internal Medicine, patients taking cilostazol at the standard dose nearly doubled their pain-free walking distance over 24 weeks, going from about 70 meters to roughly 138 meters on a treadmill. That’s a 59% improvement compared to just 20% with a placebo. Even at a lower dose, patients increased their pain-free distance by 48%.
Those numbers matter in practical terms. For someone who currently has to stop every block or two, a near-doubling of pain-free distance can mean the difference between struggling with daily errands and walking comfortably to a nearby store. The benefits tend to build gradually. Most people notice meaningful improvement over several weeks rather than days, and clinical trials measured outcomes at 12 to 24 weeks of consistent use.
How Cilostazol Works in the Body
Cilostazol blocks an enzyme called phosphodiesterase 3 (PDE3). Normally, this enzyme breaks down a signaling molecule (cAMP) that keeps platelets calm and blood vessels relaxed. By blocking that breakdown, cilostazol lets cAMP accumulate, which has two key effects: blood vessels widen, and platelets become less likely to clump together and form clots.
This mechanism is distinct from how aspirin or clopidogrel work. Those drugs act on entirely different pathways, which is why cilostazol can sometimes be used alongside them. Notably, research from the American Heart Association found that cilostazol’s ability to reduce platelet clumping is comparable to aspirin’s, yet it carries a lower risk of bleeding complications.
Off-Label Use in Stroke Prevention
Outside its approved indication, cilostazol has been studied for secondary stroke prevention, particularly in East Asian populations where it has seen wider clinical use. Its antiplatelet properties and lower bleeding risk make it an appealing option for people who have already had a stroke and need long-term protection against another one. While this use is not FDA-approved, it reflects active clinical interest in the drug’s broader vascular benefits.
How to Take It
The standard dose is 100 mg taken twice daily, at least 30 minutes before or two hours after breakfast and dinner. Timing around meals matters because food affects how the drug is absorbed. Taking it on an empty stomach ensures consistent blood levels.
Certain medications interfere with how your liver processes cilostazol, effectively increasing its concentration in your blood. If you take antifungal drugs like ketoconazole, certain antibiotics like erythromycin or clarithromycin, the blood pressure medication diltiazem, the acid reflux drug omeprazole, or the antidepressant fluoxetine, your dose will typically be cut in half to 50 mg twice daily. Grapefruit juice has the same effect and should be avoided or discussed with your prescriber.
Common Side Effects
Headache is the most frequently reported side effect, and it can be significant enough that some people stop taking the medication. Other common effects include dizziness, a pounding or fast heartbeat, diarrhea or gas, back pain, muscle stiffness, and nasal congestion. Many of these stem directly from the drug’s blood-vessel-relaxing action and tend to ease after the first few weeks as your body adjusts.
A fast or irregular heartbeat is worth paying attention to. While palpitations are common and often harmless with cilostazol, a persistently irregular rhythm should be reported to your prescriber.
The Heart Failure Warning
Cilostazol carries a boxed warning, the FDA’s most serious safety label, because it is contraindicated in people with heart failure of any severity. The concern comes from the drug’s class: other PDE3 inhibitors have been shown to decrease survival in patients with moderate to severe heart failure. While cilostazol itself hasn’t been proven to cause the same outcome, the FDA applies the warning as a precaution based on the shared mechanism. If you have heart failure, this medication is off the table entirely.
Cilostazol as Part of a Bigger Plan
Cilostazol works best as one piece of a broader strategy for managing peripheral artery disease. Walking programs, in particular, are a powerful complement. Structured exercise, where you walk to the point of discomfort, rest, and repeat, trains your muscles to use oxygen more efficiently and can stimulate the growth of small collateral blood vessels around blockages. Combining cilostazol with a consistent walking routine typically produces better results than either approach alone.
Smoking cessation is equally critical. Tobacco use is the single strongest modifiable risk factor for PAD progression. Managing cholesterol, blood pressure, and blood sugar (if you have diabetes) all help slow the underlying arterial disease that cilostazol can’t reverse on its own.