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Nasal Sprays

Emerging evidence shows that nasal sprays with some specific ingredients may lower risk of Covid-19 infection and reduce viral load during infection when used regularly.

However, for balance it is important to state that reduced viral load in the airways may not mean reduced viral load everywhere in the body and there is a lack of research on effects/safety of some sprays long term.

Nitric Oxide (NO)

  • A phase II randomised clinical trial in patients with mild Covid-19 infection found use of NO nasal spray reduced viral load by 95% on average in 24 hours, and by more than 99% in 72 hours. (Winchester et al., 2021 doi: 10.1016/j.jinf.2021.05.009)


  • A retrospective study on people with confirmed exposure to Covid-19 found that those who used NO nasal spray were 75% less likely to develop Covid-19 infection. ( Note that this is not published in a peer reviewed article and may be subject to bias)

  • A phase III randomised clinical trial in high risk, unvaccinated patients with Covid-19 tested regular use of a nasal spray containing NO. Results showed detectable viral RNA (a method of measuring virus presence) in the nose reduced by 99% within 48 hours. (Tandon et al., 2022 doi: 10.1016/j.lansea.2022.100036)

  • A study on Covid-19 infected cells in a lab found that NO is able to inhibit replication of the virus. (Akaberi et al., 2020 doi: 10.1016/j.redox.2020.101734)

  • Nitric Oxide nasal spray is not yet available in the UK, but may be in the future under the brand name SaNOtize

    • It is currently available in Israel and Indonesia under the brand name Enovid

    • In Thailand, Singapore, Hong Kong, South Africa and Germany under the brand name VirX

    • And in India (by prescription) by the brand name FabiSpray

    • (


Astrodrimer Sodium 1%

  • In lab-grown cells, Astrominer Sodium 1% is able to significantly reduce infectivity of multiple strains of SARS-COV2 (Paull et al., 2021 doi: 10.1016/j.antiviral.2021.105089)


  • Researchers gave mice a first dose of Astrodrimer Sodium 1% nasal spray alongside being infected with SARS-COV2, then gave the nasal spray for the next 6 days. Compared to controls, mice using the Astrodrimer Sodium 1% nasal spray showed 99.9% less viral genome copies and 95% less infectious virus in the lungs and windpipe. Note: only 3 mice were used per group, which is a very small sample size and could alter results. (Paull et al., 2021 doi: 10.3390/v13081656)

  • A study found that frequent use of Astrodimer Sodium 1% nasal spray for 2 weeks produced only mild side effects such as headache and a runny nose in some. They did not detect any systemic absorption of the spray through the lining of the nose, meaning the ingredients are unlikely to cause any full body effects. (Castellarnau et al., 2022 doi: 10.1038/s41598-022-14601-3)

  • The nasal spray Viraleze contains Astrodimer Sodium and is available to buy in the UK over the counter. (


  • A study in 394 healthcare professionals treating Covid-19 patients found that they were 79.8% less likely to test positive for Covid when using the Iota-Carrageenan nasal spray compared to a placebo. (Figueroa et al., 2021 doi: 10.2147/IJGM.S328486)


  • Nose and mouth sprays containing iota-carrageenan suppress infection of lab-grown human airway-lining cells by SARS-COV2 virus (Schutz et al., 2021 doi: 10.1152/ajplung.00552.2020)


  • Iota-carrageenan can prevent spike protein-mediated infection of lab-grown cells by Covid-19 virus particles. This is more effective at higher doses. (Morokutti-Kurz et al., 2020 *preprint; doi: 10.1101/2020.07.28.224733)


  • A review of iota-carrageenan use within food, usually as a stabiliser or thickener, finds it is safe to consume. It concludes that is is not significantly absorbed or metabolised, nor does it show any toxic effects. (Weiner 2014, doi: 10.3109/10408444.2013.861798)


  • A randomised controlled trial showed that in common colds caused by other coronaviruses, iota carrageenan nasal spray increased recovery rate by 139%. The authors hypothesize that it may have a similar effect on Covid-19. (Hemila and Chalker 2021; doi: 10.1002/prp2.810)


  • A number of brands offer iota-carrageenan nasal sprays under different names. The best known UK brand is Boots Dual Defence nasal spray.


Example nasal spray containing carrageenan, other brands are available

Mouth Washes/Sprays

Inhalation of virus particles is through both the nose and mouth, so it is also worth considering mouth washes and sprays which may reduce infection. These are another layer of protection and shouldn't be considered a reason to not wear a mask, as they do not guarantee you won't be infected with Covid-19.

Cetylpyridinium chloride (CPC)

Screenshot 2023-04-11 192249.png

Examples of products containing CPC, other brands are available

  • CPC, at concentrations usually found in mouthwash, was found to be able to rupture the membranes of SARS-COV2 virus-like particles within the lab. (Bañó-Polo et al., 2022 doi: 10.1080/20002297.2022.2030094)


  • In the lab, CPC mouthwash reduces the infectivity of Covid-19 by damaging the outermost layer of the viral particles, preventing them from binding to and infecting cells. (Muñoz-Basagoiti et al., 2021 doi: 10.1177/00220345211029269)


  • Study finds that even low concentrations of CPC suppressed the activity of multiple Covid-19 strains when mixed in with saliva. (Takeda et al., 2022 doi: 10.1038/s41598-022-18367-6)


  • A review of randomised controlled trials concludes that CPC use is able to reduce the amount of Covid-19 within the saliva. They also hypothesise it may be able to reduce transmisibility and severity of Covid-19 infection in people already infected.
    (D'Amico et al., 2023 doi: 10.1111/omi.12408)


  • Mouthwashes containing CPC are widely available in the UK. Brands include Colgate, Dentyl, Oral-B and Boots. Some brands also sell mouth sprays containing CPC as an alternative.

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