Flavanones are a subclass of flavonoids commonly found in citrus fruits such as oranges, lemons, and grapefruits. There is some scientific evidence indicating that flavanones, particularly hesperidin and naringenin, have antiviral activity and may provide modest support in the management of colds. Laboratory studies have shown that these compounds can inhibit the replication of certain viruses, including rhinoviruses and influenza viruses, which are common causes of the common cold. The proposed mechanisms include modulation of immune system responses, antioxidant effects, and interference with viral entry or replication.

However, most of the evidence supporting flavanones for colds comes from in vitro (test tube) or animal studies, rather than well-controlled human clinical trials. Some small-scale human studies suggest that citrus-derived flavonoids may slightly reduce the duration or severity of cold symptoms, but results are inconsistent and clinical relevance remains unclear. There is a tradition of using citrus fruits (rich in flavanones) for cold relief, but the justification for their use is primarily based on their biochemical properties and preliminary scientific studies.

In summary, while there is some scientific groundwork suggesting potential antiviral effects of flavanones, high-quality clinical evidence is limited. Thus, the evidence rating for the use of unspecified flavanones to treat or support colds is moderate to low.