ColdZyme is a medical device based on research into how respiratory viral infections occur, and how they can be stopped at an early stage. In clinical studies, ColdZyme has been shown to relieve symptoms and shorten the duration of a cold.
The mechanism of action is mechanical: ColdZyme forms a protective and osmotically active moisture layer in the throat. This makes it harder for viruses to attach to the mucous membrane and enter the body. Instead, viruses are trapped and inactivated locally, reducing the risk of the infection developing fully.
Here you can read more about the research demonstrating the efficacy and safety of ColdZyme.
ColdZyme® reduces cold duration and symptoms
A randomized, double-blind, placebo-controlled study published in The Journal of Physiology shows that ColdZyme not only relieved 6 of 8 cold symptoms but also reduced the number of sick days. In the in vitro part of the study, ColdZyme demonstrated clear protection against viruses — viral load decreased by 94% on the mucosal membrane and the cells' protective surface layer was preserved. Viral analysis confirmed that participants' symptoms were caused by cold viruses, primarily rhinovirus.
Davison G et al. The Journal of Physiology, 2025;603(6):1483–1501. doi: https://doi.org/10.1113/JP288136
Researchers explain the results of the latest study
Professor Glen Davison and Professor Doris Wilflingseder provide a concise overview of the results from the study published in February. The presentation is in English and has a scientific tone, aimed at those who wish to explore the study in depth.
Study shows good safety profile — but no differences in primary endpoints
A randomized, double-blind, placebo-controlled study conducted at 10 sites in Germany, published in PLOS ONE in 2023, found no significant differences in primary endpoints between ColdZyme and placebo with regard to experienced cold symptoms. Participants (n=438) rated their symptoms daily using the WURSS-21 and Jackson scales. However, an exploratory analysis suggests that ColdZyme may have accelerated recovery by approximately one day, with the beneficial effect particularly noticeable on day five of the cold. The absence of viral analysis and the fact that the study was conducted in spring may have influenced the results, as some symptoms could have been caused by, for example, allergies. The study confirms that ColdZyme is safe to use.
Lindberg BF, Nelson I, Ranstam J, Riker DK. PLoS ONE, January 2023;18(1):e0279204. doi: https://doi.org/10.1371/journal.pone.0279204
ColdZyme reduced symptoms and improved quality of life during a cold
A randomised, prospective, parallel-group study published in PLOS ONE examined the effect of starting ColdZyme at the very first signs of a cold. Participants (treatment group vs. untreated control group) recorded their symptoms and quality of life over twelve days using the Jackson scale and the WURSS-21 quality of life instrument. Those who received ColdZyme experienced a significant reduction in symptoms compared to those who received no treatment (p=0.006). They also had improved quality of life and a reduced need for symptom-relieving medicines during the first four days (35.3% vs. 50.4%, p=0.014).
Lindberg F, Nelson I, Ranstam J, Riker DK. PLoS ONE, July 2022;17(7):e0270699. doi: https://doi.org/10.1371/journal.pone.0270699
ColdZyme shortens cold symptom duration in elite athletes
A randomised, controlled study published in the European Journal of Sport Science examined the effects of ColdZyme on upper respiratory tract infections in competitive endurance athletes (n=123) under real-world conditions over two winter seasons. Athletes who used ColdZyme as instructed experienced significantly shorter illness duration compared to the untreated control group: 7.7 ± 4.0 days vs. 10.4 ± 8.5 days (p=0.016), a reduction of 26%. Among those with good compliance with instructions for use, duration was further reduced to 6.9 days, which was 34% shorter than controls (p=0.004). The ColdZyme group also had significantly fewer lost training days per illness episode: 1.6 vs. 3.5 days (p=0.013).
Davison G, Perkins E, Jones AW, et al. European Journal of Sport Science, 2021;21(5):771–780. doi: https://doi.org/10.1080/17461391.2020.1771429
An open-label survey study published in the Open Journal of Respiratory Diseases followed 13 competitive athletes over three months while they used ColdZyme to prevent or relieve colds. During the study, 15 cold episodes were reported with an average duration of 7.4 days. 81% experienced their colds as shorter or milder than usual; none reported "no effect". 87.5% were able to continue training, either as usual or at reduced intensity. As the study lacked a control group, a placebo effect cannot be excluded and the results should be interpreted with caution.
Blom U, Nelson I. Open Journal of Respiratory Diseases, 2018;8(2). doi: https://doi.org/10.4236/ojrd.2018.82002
ColdZyme linked to fewer sick days among healthcare workers
An open observational study published in the Open Journal of Respiratory Diseases evaluated ColdZyme among personnel at elderly care facilities during one winter season. Compared to the preceding winter, the average number of short-term sick days per person decreased by 29%, from 5.2 to 3.7 days (p=0.054). 63% of those who experienced a cold reported milder symptoms than usual. As the difference did not reach conventional statistical significance (p<0.05) and the comparison was made against historical data rather than a concurrent control group, the results should be interpreted with caution.
Clarsund M, Persson C. Open Journal of Respiratory Diseases, 2017;7(1):12–17. doi: https://doi.org/10.4236/ojrd.2017.71002
Fewer sick days and milder symptoms among elite athletes using ColdZyme
An open observational study published in the Open Journal of Respiratory Diseases evaluated ColdZyme among Swedish elite athletes in biathlon (n=11), ice hockey (n=29) and handball over several winter seasons. The biathlon team reduced cold-related sick days from 7.0 to 3.5 days per season (p=0.04) and the ice hockey team reduced sick days per month by 67% (p=0.02), both compared to historical control periods. 76% of handball players reported little or no impact on training when ill. Athletes who got a cold reported milder symptoms and improved quality of life. As comparisons were made against historical data, results should be interpreted with caution.
Clarsund M. Open Journal of Respiratory Diseases, 2017;7(3):103–109. doi: https://doi.org/10.4236/ojrd.2017.73010
ColdZyme reduced viral load and shortened duration of symptoms
In a randomized, double-blind, placebo-controlled pilot study, healthy volunteers were infected with cold virus and treated with either ColdZyme or placebo six times daily for 11 days. Not all participants developed a cold, and exploratory efficacy analyses were performed on only on those with confirmed infection. In this group, ColdZyme treatment was associated with a significant reduction in pharyngeal viral load (p=0.02). Among those who developed symptoms, the median duration of cold symptoms was 3.0 days in the ColdZyme group compared with 6.5 days in the placebo group, a reduction of 54%.
Clarsund M, Fornbacke M, Uller L, Johnston SL, Emanuelsson CA. Open Journal of Respiratory Diseases, 2017;7(4):125–135. doi: https://doi.org/10.4236/ojrd.2017.74013
ColdZyme linked to fewer sick days among preschool staff
An open observational study published in the Open Journal of Respiratory Diseases followed 15 preschool staff members in Sweden over one winter season (October–March) while they used ColdZyme. Sick leave days were recorded and compared to the preceding year's historical data. The average number of cold-related sick days per person decreased significantly from 7.4 to 4.1 days (p=0.04). Most participants who did get a cold experienced milder symptoms than usual. As comparisons were made against historical data rather than a concurrent control group, results should be interpreted with caution.
Clarsund M. Open Journal of Respiratory Diseases, 2017;7(4):136–140. doi: https://doi.org/10.4236/ojrd.2017.74014
ColdZyme shows broad antiviral activity against cold viruses in laboratory tests
In this in vitro study (laboratory test) published in Virology: Research & Reviews ColdZyme was tested against four common respiratory viruses using a cytopathic host cell incubation assay. Viral activity was reduced by 91–99% for two strains of rhinovirus, influenza A (H3N2) and respiratory syncytial virus (RSV), and by 64% for adenovirus type 2. The results indicate that ColdZyme has broad antiviral activity against multiple virus types associated with common cold and influenza-like symptoms. As an in vitro study, results cannot be directly translated into a clinical setting.
Stefansson B, Gudmundsdottir Á, Clarsund M. Virology: Research & Reviews, 2017;1(5):1–3. doi: https://doi.org/10.15761/VRR.1000130
