Over-the-counter nasal sprays cut respiratory infections by 20%, study finds

University of BristolJul 12 2024

Widely available over-the counter nasal sprays could keep upper respiratory tract infections - like colds, chest infections, flu, sore throat, and sinus infections - at bay, and prevent full-blown symptoms from developing, one of the largest trials to date to test their effectiveness finds. The research, which analyzed data from nearly 14,000 adults, found overall they reduced the days of illness by around 20 per cent, and also reduced the number of days with severe symptoms, time off work or normal activities, and antibiotic use.

The study led by the University of Southampton in collaboration with the University of Bristol, and funded by the National Institute for Health and Care Research (NIHR), is published in The Lancet Respiratory Medicine today [12 July].

There is some recent evidence that using nasal sprays to wash out virus from the nose and throat, or improving immune function through increasing exercise and managing stress, could reduce the frequency and severity of respiratory infections. To investigate this, researchers undertook a large-scale randomized trial to compare the effectiveness of two different types of nasal spray and an online resource providing advice on physical activity and stress management.

Researchers recruited 13,799 adult patients from 332 GP practices. All patients had an existing health problem or risk factor for infection, and/or recurrent respiratory infections in the past. Patients were randomized to receive one of three interventions. These were: a Vicks-First-Defence gel-based nasal spray - which uses a microgel to trap viruses, and neutralizes the viruses in the nose helping to prevent the virus from developing and spreading; a saline liquid-based nasal spray - which reduces levels of virus in the nasopharynx; or an online resource promoting physical activity and stress management.

All three interventions reduced antibiotic use (a relative risk reduction of more than 25 per cent) and also the number of days with more severe symptoms. Even though participants did not use the sprays as often as they were asked to, both sprays were shown to reduce the overall illness duration participants experienced by around 20 per cent, and resulted in a 20-30 per cent reduction in the days lost of work or normal activity.

In comparison, the behavioral physical activity and stress management online advice reduced the incidence of infections by a modest five per cent relative reduction. However, this cost-effective option could have a significant impact in population terms given how easy it is to provide online advice to the general public.

Paul Little, Professor in Primary Care Research from the University of Southampton, who led the trial, said: "Our results show nasal sprays work well to reduce the duration and severity of respiratory infections, and the interference with normal activities, which is particularly important in light of the winter infection surge the UK regularly experiences. The important finding of a reduction in the use of antibiotics is also potentially very important in the fight against antibiotic resistance, one of the major public health threats of our time.

"Given these results, our advice, particularly for those at higher risk from infections or those who get recurrent infections, is at the first sign of cough, sore throat, cold or flu like symptoms, use a nasal spray to prevent it from developing fully, and to use the sprays preventatively after close exposure to people with infections."

Lucy Yardley, OBE, Professor of Health Psychology at the Universities of Bristol and Southampton, who led the nasal spray part of the study, added: "Our analysis suggests that the benefits were even greater when people used the sprays more often - we advised six times a day at the first sign of a cold - but many people in the study did not use the spray that often."

Dr Adam Geraghty, Associate Professor of Psychology and Behavioural Medicine at the University of Southampton, who led the exercise and stress reduction part and co-led the study, explained: "If widely used these interventions could potentially have a valuable role for reducing antibiotic use and antimicrobial resistance, and in reducing the impact of respiratory viruses for patients, the health service and the wider economy."

The study was funded by the NIHR Programme Grants for Applied Research (RP-PG-0218-20005) with support from NIHR Health Protection Research Unit (HPRU) in Behavioural Science and Evaluation and NIHR Applied Research Collaboration West (ARC West).

The views expressed are those of the authors and not necessarily those of the NIHR or the Department of Health and Social Care.