Which statement is true about hemorheologic agents?

Hemorheologic agents are designed to alter the flow properties of blood, primarily by decreasing blood viscosity. This is crucial in enhancing blood flow, especially in conditions where blood flow is compromised. By improving the flexibility of red blood cells and reducing aggregation, these agents promote better circulation, which can be particularly beneficial in treating peripheral vascular diseases.

The other statements do not accurately reflect the characteristics and effects of hemorheologic agents. For example, while they do work to lower viscosity, stating they have no side effects is misleading, as any medication can have potential adverse effects. Additionally, these agents are indeed used for peripheral vascular disease, contrary to the claim that they are not. Thus, the assertion that hemorheologic agents improve blood flow and lower viscosity is a true and accurate representation of their function in pharmacology.