Despite seeming to be unrelated, the amount of hair loss you have has an effect on how severely COVID affects you. Doctors noticed that men who tended to be bald on admission for COVID had far worse outcomes.1 It has taken more in depth research to understand how and why that is.
Researchers have found that those with androgenetic alopecia (male and female pattern hair loss), have a higher chance of getting severe COVID. Persons with androgenetic alopecia have higher levels of dihydrotestosterone (DHT). In addition to causing hair loss, DHT also causes lung cells to make more of an enzyme called transmembrane protease serine 2 (TMPRSS2). The virus that causes COVID-19 latches onto lung cells containing the TMPRSS2 enzyme and is activated by it.2
Unfortunately, TMPRSS2 is present in higher amounts in the cells of men. Women and children do not make the same amounts of TMPRSS2 which explains why they have lower chances of getting COVID-19. Furthermore, women and pre-pubertal children have low levels of androgen receptors that receive signals from DHT. When androgen receptors are activated, cells have greater Angiotensin Converting Enzyme 2 (ACE2) activity which SARS-CoV 2 also binds to.3
Does this mean that DHT blockers are helpful for hair as well as COVID? Based on a number of studies it does appear so.
One small study treated 50 men who had just been diagnosed with COVID with either placebo or the prescription DHT Blocker finasteride. Researchers found that the group that received finasteride had better oxygen saturation than the placebo group but no meaningful difference in mortality rate. This study did not find DHT blockers to be helpful if used just after catching COVID.4 However, this is due to the length of time it takes for DHT blockers to start working.
Another study went back and found that men who were already using 5-alpha-reductase inhibitor drugs reported less symptoms than men not using DHT blocking drugs.5 Unfortunately this study is subjective because it surveyed patients regarding their symptoms.
The most definitive study on this topic looked at men hospitalized for COVID-19 found that men who had taken DHT Blockers for 6 months prior to hospitalization compared to men who did not had lower rates of ICU admission. After correcting for differences in age, 8% of men taking DHT blockers were admitted to the ICU for COVID versus 47.2% of men not taking DHT Blockers.6 This is quite a substantial difference between the two groups and highlights the role of DHT in COVID.
The key takeaway from these findings is that DHT blockers may be helpful for COVID, especially if they are taken for a period of time before someone is infected by the SARS-CoV 2.