Final answer:
The patient is likely using echinacea for immune system support, despite limited evidence regarding its efficacy in treating respiratory infections.
Step-by-step explanation:
The patient taking echinacea is most likely doing so to support her immune system. While various alternative treatments exist for the common cold, a 2007 review suggests that treatments like echinacea, vitamin C, and zinc are not recommended for treating cold symptoms. However, it also notes that vitamin C may marginally reduce the duration and severity of a cold. A 2014 review concurs that there is insufficient evidence to support the effectiveness of echinacea in this regard.
Clinical cases are often referenced to highlight the use of over-the-counter medications and alternative treatments in response to respiratory symptoms such as coughs and fever. This context mirrors real-life scenarios where individuals might consider echinacea for similar symptoms. Nonetheless, it should be emphasized that the efficacy of echinacea in treating respiratory infections such as influenza, bronchitis, pneumonia, or other diseases that might cause fever and cough remains unsupported by strong scientific evidence.
Nevertheless, the popularity of echinacea persists, perhaps due to its perceived benefits in immune system support, which might explain why the patient in the question believes in using it. To sum up, based on available reviews and clinical context, the most appropriate answer to the patient's suspected treatment with echinacea would be option c) Immune system support.