Hi & Welcome to HCM. The effect may persist 7-10 days after stopping Pentoxifylline. Pentoxifylline is used to improve blood flow in patients with Intermittent claudication (circulation problems) to reduce aching, cramping, & tiredness in the hands and feet. It works by decreasing the thickness (viscosity) of blood and by reducing the platelets aggregation which helps to improve blood flow. This increases the amount of oxygen that can be delivered by the blood when the muscles need more (such as during exercise). Although rare, severe isolated thrombocytopenia can occur as a side effect while taking Pentoxifylline. Since the lifespan of platelets is 7-10 days, so it it may take 7-10 days to recover from the platelet deaggregation effect. Hope this answer your query.