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While the coronavirus vaccine has been available for some time, catching the virus is still serious business. You may have heard about a potential treatment for COVID-19: sildenafil (brand name Viagra; see Important Safety Information). While sildenafil might be a miracle treatment when it comes to erectile dysfunction, it hasn’t been proven to be an effective treatment for COVID-19. However, one study does indicate sildenafil could decrease the need for IMV (invasive mechanical ventilation, or a ventilator) in certain COVID-19 patients (Santamarina, 2022). Read on to learn more.
Does sildenafil treat coronavirus?
Sildenafil is not a coronavirus cure, and is not currently considered a treatment for COVID-19.
However, there’s ongoing research to see if sildenafil can help COVID patients breathe better and reduce the need for hospitalization or ventilators. In one study of 40 participants, four who received a placebo treatment needed a ventilator, while none of the participants who received sildenafil did (Santamarina, 2022). More research is needed to prove a connection. Other researchers have outlined why they think this prescription drug would be able to help with COVID-19, but the evidence is limited (Mario, 2020).
How does Viagra work?
Sildenafil is the active ingredient in Viagra, and the generic version of the medication is often sold by the simple name, sildenafil. Sildenafil belongs to a class of drugs called PDE-5 inhibitors (phosphodiesterase-5 enzyme inhibitors). These drugs block an enzyme called PDE-5, which allows more blood to flow to your penis. Increased blood flow to the penis means that with sufficient arousal or sexual stimulation, you may be able to get firmer erections that last longer.
How sildenafil could impact coronavirus
Sildenafil is not only used to treat erectile dysfunction. The drug has also been approved to treat a lung condition called pulmonary arterial hypertension, under the brand name Revatio. This rare condition is characterized by high blood pressure in the blood vessels that supply the lungs. Sildenafil has been shown to lower the pressure in those blood vessels, alleviating symptoms and preventing disease progression (Bhogal, 2019).
So, how does sildenafil (potentially) work when it comes to reducing the need for ventilators in COVID-19 patients? Most prominently, research shows that the drug reduces immune system activity in rat models (Kosutova, 2018). This may be particularly important to COVID-19 patients because most lung damage caused by severe COVID-19 often results from the immune system trying to kill the virus, not caused by the virus itself (Chen, 2020).
Additionally, there is evidence that nitric oxide (NO), which causes the blood vessels to dilate, might contribute to a better prognosis in patients with severe COVID-19. While sildenafil doesn’t seem to increase nitric oxide levels directly, it has some of the same effects as the molecule (Dal Moro, 2020).
There is also some research showing that higher nitric oxide levels might block some coronaviruses from replicating in the lungs and causing damage (Åkerström, 2005). Some healthcare providers have even explored the use of nitric oxide itself as a treatment for patients with severe COVID-19 (Bagate, 2020).
This research is certainly interesting, but none of these treatments have been approved for this use. So, if you have coronavirus and start to experience breathing issues, seek medical help immediately and don’t attempt to treat any symptoms on your own.
- Akerström, S., Mousavi-Jazi, M., Klingström, J., et al. (2005). Nitric oxide inhibits the replication cycle of severe acute respiratory syndrome coronavirus. Journal of Virology, 79(3), 1966–1969. doi:10.1128/JVI.79.3.1966-1969.2005. Retrieved from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC544093/
- Bagate, F., Tuffet, S., Masi, P., et al. (2020) Rescue therapy with inhaled nitric oxide and almitrine in COVID-19 patients with severe acute respiratory distress syndrome. Annals of Intensive Care 10, 151. Retrieved from https://annalsofintensivecare.springeropen.com/articles/10.1186/s13613-020-00769-2
- Bhogal, S., Khraisha, O., Al Madani, M., et al. (2019). Sildenafil for pulmonary arterial hypertension. American Journal of Therapeutics, 26(4), e520–e526. doi:10.1097/MJT.0000000000000766. Retrieved from https://pubmed.ncbi.nlm.nih.gov/30946047/
- Chen, L. Y., Hoiland, R. L., Stukas, S., et al. (2020). Confronting the controversy: Interleukin-6 and the COVID-19 cytokine storm syndrome. European Respiratory Journal, 56(4), 2003006. doi:10.1183/13993003.03006-2020. Retrieved from https://erj.ersjournals.com/content/early/2020/08/28/13993003.03006-2020
- Dal Moro, F., Vendramin, I., & Livi, U. (2020). The war against the SARS-CoV2 infection: is it better to fight or mitigate it? Medical Hypotheses, 143, 110129. doi:10.1016/j.mehy.2020.110129. Retrieved from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7373683/
- Kosutova, P., Mikolka, P., Balentova, S., et al. (2018). Effects of phosphodiesterase 5 inhibitor sildenafil on the respiratory parameters, inflammation and apoptosis in a saline lavage-induced model of acute lung injury. Journal of Physiology and Pharmacology: An Official Journal of the Polish Physiological Society, 69(5). doi:10.26402/jpp.2018.5.15. Retrieved from https://pubmed.ncbi.nlm.nih.gov/30683832/
- Mario, L., Roberto, M., Marta, L., et al. (2020). Hypothesis of COVID-19 therapy with sildenafil. International Journal of Preventive Medicine;11:76. doi:10.4103/ijpvm.IJPVM_258_20. Retrieved from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7478270/
- Santamarina, M. G., Beddings, I., Lomakin, F. M., et al. (2022). Sildenafil for treating patients with COVID-19 and perfusion mismatch: a pilot randomized trial. Critical care (London, England), 26(1), 1. doi:10.1186/s13054-021-03885-y. Retrieved from https://pubmed.ncbi.nlm.nih.gov/34980198/
Dr. Chimene Richa is a board-certified Ophthalmologist and Senior Medical Writer/Reviewer at Ro.