Brief overview Current evidence from published systematic reviews indicate that oral intake of vitamin C may assist with symptoms of acute viral respiratory infections (ARI) by reducing fever and chills, relieving chest pain and assist in reducing symptoms of common cold-induced asthma. Intravenous (IV) vitamin C administration may reduce the need for vasopressor support and the duration of mechanical ventilations in critically ill patients in hospital. COVID-19 has similar signs and symptoms of ARI. Further studies involving patients with COVID-19, either through administration of oral vitamin C in mild cases or IV vitamin C in critical cases, would be advantageous to examine if it is safe and efficacious.

Verdict Oral vitamin C may assist with the symptoms of acute respiratory viral infections (ARI) and common cold-induced asthma but no studies have been identified justifying oral vitamin C for the prevention or treatment of coronavirus infections including COVID-19. When taken at onset of ARI, oral vitamin C may reduce the duration of symptoms including fever, chest pain, chills and bodily aches and pains. It may also reduce the incidence of hospital admission and duration of hospital stays. For individuals admitted to hospital with community-acquired pneumonia, vitamin C may improve respiratory function in more severe cases. No major adverse events nor interactions were reported by either method of administration. However, there is an absence of high quality, contemporary clinical research examining this topic. Current evidence suggests further studies are needed to better understand the value of both oral and IV vitamin C for ARI, including COVID-19.