In times of health crisis, including the current COVID-19 pandemic, the
potential benefit of botanical drugs and supplements emerges as a focus
of attention, although controversial efficacy claims are rightly a
concern. Phytotherapy has an established role in everyday selfcare and
health care, and since botanical preparations contain many chemical
constituents rather than single compounds, challenges arise in
demonstrating efficacy and safety. However, there is ample traditional,
empirical and clinical evidence that botanicals can offer some
protection and alleviation of disease symptoms as well as promoting
general well-being. Newly emerging viral infections, specifically
COVID-19, represent a unique challenge in their novelty and absence of
established antiviral treatment or immunization. We discuss here the
roles and limitations of phytotherapy in helping to prevent and address
viral infections, and specifically regarding their effects on immune
response. Botanicals with a documented immunomodulatory,
immunostimulatory, and anti-inflammatory effect include adaptogens,
Boswellia spp., Curcuma longa, Echinacea spp., Glycyrrhiza spp.,
medicinal fungi, Pelargonium sidoides, salicylate-yielding herbs, and
Sambucus spp. We further provide a clinical perspective on applications
and safety of these herbs in prevention, onset, progression, and
convalescence from respiratory viral infections.