A few weeks ago, I ended up getting a cold that lasted forever. I’m talking about weeks of coughing, nasal congestion, and multiple boxes of tissues. At the same time, someone in my writers’ group shared that an iota carrageenan nasal spray helped her get over her cold quickly. She pointed me to a paper and of course, I went down a rabbit hole looking up this seemingly magic spray and what research backs up its healing powers.
I did a quick search on PubMed for “Carrageenan nasal spray” and it gave me 31 publications. From scrolling through these publication tiles, what became clear to me is that it’s not only for colds.
What is carrageenan?
Carrageenan is a type of sugar known as a sulfated polysaccharide. It’s extracted from red edible seaweed and you may have heard of it in other contexts as it is widely used in the food industry as a gelling and thickening agent. Carrageenan does have a microbiology connection since it has been explored as an alternative to using agar as a bacterial growth medium. However, it has lower melting and setting temperatures and is less ideal for preparing Petri dishes.
Carrageenan can be classified into three types based on the number of sulfate groups they contain. Iota-carrageenan, which has two sulfate groups, has been the focus of many of the studies discussed below.
How do carrageenan nasal spray help against respiratory infections?
The general idea is that carrageenan sprays provide a protective barrier inside the nose to prevent viruses from infecting our cells. Birmingham Biotech, which markets a spray with gellan gum and iota-carrageenan claims that their spray creates a gel-like layer on the nasal surfaces which traps particles that are subsequently removed from the body. Unither Pharma claims that their carrageenan product works as a purely physical barrier, acting as a barrier while providing moisture to the mucosal surface.
There have been several studies that show this barrier function. In the early days of the COVID-19 pandemic, scientists started seeing whether carrageenan can help treat COVID-19 and three papers published in 2021 to 2022 looked at how the spray interacted with SARS-CoV-2 (the studies can be found here, here, and here). They found that nasal and oral versions of carrageenan sprays inhibited the virus from entering human cell cultures . Another study tested the spray against the original SARS-CoV-2 strain and subsequent variants in a human lung cell model. They found that carrageenan as a nasal or mouth spray, or as a lozenge, had antiviral activity.
A word of caution:
Despite the positive effects of carrageenan on relieving COVID-19 symptoms, one study finds that a carrageenan spray interfered with COVID-19 PCR tests and leads to false negatives, depending on the diagnostic platform used.
Effectiveness of carrageenan against upper respiratory infection symptoms
As I alluded to above, the current evidence finds that carrageenan sprays can be effective against colds, flu, COVID-19, and even allergies. In terms of symptoms, I came across multiple clinical studies that for the most part, show that these sprays are effective in either reducing symptom severity or symptom duration.
One study mentioned that carrageenan shortened the duration of longer lasting colds, but not shorter colds. Another clinical trial found that a carrageenan spray reduced the duration of cold symptoms. The researchers involved in this study also analyzed nasal wash fluid and found fewer viruses and fewer proinflammatory molecules in the fluid.
Shortening congestion symptoms? Yes, please! Image: Andrea Piacquadio
When it comes to the flu, carrageenan spray seemed to improve treatment of influenza A infection when paired with an antiviral drug used to treat influenza. This study showed that the combination of carrageenan and the antiviral increased survival of infected mice compared to carrageenan or antiviral alone or without any treatment. This survival benefit occurred even when they started therapies up to 72 hours after infection.
Though there have been fewer studies of carrageenan’s effect on allergy symptoms, one study explored how carrageenan affects the “total nasal symptom score” which looks at nasal discharge, itching, sneezing, and congestion. Just three hours after carrageenan treatment, the researchers found that carrageenan reduced this score and that there were fewer nasal secretions.
Can carrageenan spray everyday prevent respiratory illnesses?
Because the idea behind carrageenan is that it coats the nasal passages and prevents viruses from infecting us, would taking carrageenan as a preventative help? Researchers looked at how a three times a day spray for eight weeks affected upper respiratory tract symptoms and saw that regular daily carrageenan did seem to reduce symptoms, but didn’t find this to be statistically significant. Therefore, we still need further trials to see if it is truly effective. The researchers of this study did note that it could be difficult for people to adhere to using a spray three times a day everyday as a preventative measure.
Unclear effective of carrageenan in treating common colds in children
In contrast to the above studies, one clinical trial found that carrageenan did not alleviate symptoms in children with the common cold, but it did reduce the amount of virus in secretions. One reason that these results are different from other studies is that it’s difficult to evaluate less visible symptoms in children like headaches or muscle aches. The mean age of the children involved in the study was five years old and most of the kids in the study were also taking an additional medication such as antiinflammatory medications, which could skew the results. The study did mention that while the result wasn’t statistically significant, it did trend towards showing a benefit with carrageenan treatment. Because the study did find that there were fewer viruses in nasal secretions, it does suggest that carrageenan is having some sort of positive effect.
One unique thing to point out about cold remedies for children, is that currently many medications including nasal decongestants are not recommended for those under 12 years. If a carrageenan spray proves effective in children, it could especially be helpful kids who don’t have as many options for symptom relief.
Share your thoughts! Does it work for you?
I have yet to give carrageenan sprays a try since I just learned about it but I might need to give it a try. With a kid in preschool, I definitely get my fair share of respiratory illnesses (I even blogged about daycare respiratory illness transmission when I was in the throes of it all). While my cold durations have generally ranged from a few days to a few weeks, perhaps I could track my symptoms for a year without any intervention and then track symptoms another year with intervention.
Have you found that the carrageenan sprays are effective for you? Let me know in the comments below!
Want more respiratory infection content? You might be interested in…
- Why do we get more colds and respiratory illnesses in the wintertime?
- When should I get my flu shot? Here’s what science says.
- Do You Really Need to Finish That Course of Antibiotics?
- Move over flu season, there’s an entire epidemic calendar
Featured image source: StinaTano. CC BY-SA 3.0.
Medical disclaimer: This website does not provide medical advice. It is intended for informational purposes only. No material on this site is intended to be a substitute for professional medical advice, diagnosis, or treatment.