The reason why bleach can NEVER cure COVID-19

I had hoped to keep this blog out of politics and focussed on science, but I don’t think I can really avoid bleach/UV-gate. People are free to have their opinions of Trump and his policies, I won’t dispute these and I’ll try my best not to be rude, but we do need to be clear on the science.

In case I’m losing/confusing people during these posts, I’m going to start putting the take-home message at the beginning. So here we go:

Take home message – bleach will NEVER work as a COVID treatment, Trump doesn’t understand science, and you shouldn’t worry if you sometimes feel like an imposter and don’t deserve to be where you are (AKA ‘imposter syndrome’).

Here is how that all fits together…

In case you spent lockdown under a rock, with no TV, internet, or phone, the picture below sums up our start point pretty well:

I initially wanted to write about this after reading comments online saying the media was just jumping on Trump because he was “promoting treatments that wouldn’t make Bill Gates money from his vaccine”, and that there were “companies developing these treatments if you look online”. As discussed previously, the way out of this situation requires us to act together – it’s important we understand why some things won’t work, so when something genuine comes along we all get behind it.

Aaaand then reports started showing people in the US actually drinking/inhaling bleach... I think it’s important to remember here that people are scared, confused and trying to protect themselves – I think it’s hard to blame them for acting out of desperation… I believe we all try to apply logic, and I think you can kind of see there may be some logic in there…

…I mean, bleach does kill COVID-19…

…Yes it’s toxic, but drugs like paracetamol and ibuprofen are toxic if you take too much…

In fact, one of the most famous sayings about toxicity is “the dose makes the poison”… Everything is toxic in high-enough doses, even water (I don’t just mean drowning here)…

…And there are genuinely companies looking at bleach/UV treatments…

…So could it be possible to take just-the-right-amount-of-bleach to kill COVID but you’d be unaffected?…

…God… Could… Could Trump actually be right?…

Short answer:


To (mis)quote Groucho Marx:

“He may talk like an idiot and look like an idiot, but don’t let that fool you: He really is an idiot.”

The term we need to understand to answer the bleach question is called a “mechanism of action”. Basically, this describes the way that something produces an effect on biology. For example, if you think of a lawnmower, it is easy to see the effect on biology: the cut grass. The ‘mechanism of action’ of a lawnmower – how the effect is produced – is by the spinning blades underneath:

Anyone else found they bloody love mowing the lawn during lockdown, or is it just me? I genuinely think I may have missed my calling in life…

So what is the ‘mechanism of action‘ for bleach/UV killing things? Well, UV is pretty easy as we all know that damages DNA, hence sunburn and skin cancer. Bleach is a bit more complex, but does all sorts of nasty stuff including breaking up biological membranes, unfolding proteins, and damaging DNA. This is important because there is nothing in this ‘mechanism of action’ that would cause bleach/UV to specifically damage COVID-19. It’s not like an antibiotic that specifically damages bacteria over human cells. Bleach would therefore have a ‘non-specific mechanism of action’ which means it is impossible to ‘treat’ someone with it without causing them harm at the same time.

Well, what about if you could take just-the-right-amount-of-bleach? So another example of a ‘non-specific mechanism of action’ is fire: Cover COVID-19 in petrol and set it on fire and that will kill it. But I hope it is really clear that there is no way in hell you could ever drink just-the-right-amount-of-petrol and set yourself just-the-right-amount-of-on-fire-internally to cure yourself of COVID-19… These non-specific mechanisms of action will NEVER work here.

Well, what about the companies you can find online trying this? Well, the whole point of search engines is that they find what you are looking for… Bleach/UV won’t work as treatments – this fact won’t change just because some people don’t understand it.

Lastly I wanted to write about what lessons we could take from Trump making this suggestion. In Post 2, I mentioned the Dunning-Kruger effect, which is a psychological effect where someone who is unskilled in a field is overly confident in their abilities because they can’t see that there’s more to the situation. As knowledge grows and the complexity of the field becomes evident, the confidence drops… You could draw a graph for this like the one below:

Credit to the Daily Star for this one!

When it comes to science, Donald Trump sits solidly in the top left of this graph – high confidence, low knowledge – an area sometimes referred to as ‘the peak of Mount Stupid‘. To be clear, it’s absolutely not a problem to be in this area – we all have to go through it to develop our knowledge. What makes the bleach suggestion remarkable is that even after months of briefings with the top scientists in the US, Trump was still in that area and hadn’t realised there’s A LOT to medicine that he doesn’t understand.

Anyway, what can the rest of us learn from this? Well, I wanted to give one final thought for anyone reading who may struggle with feeling like they don’t deserve to be where they are or are a fraud (‘imposter syndrome’). The loss of confidence from the Dunning-Kruger effect is part of the reason for this feeling. You may wonder how long does that decrease in confidence last? Well I can only speak from my own experiences in science, but my initial peak in confidence was probably the first day of my undergraduate degree. My lowest point in confidence was probably near the end of my PhD, so 8 years later, and I’m pretty sure I’m not alone in that timescale. ‘Imposter syndrome’ is really common in science and I guess also when developing expertise in any field (please correct me if I am wrong people in other fields!). Decreasing confidence despite working hard on something is really painful, but it’s still a part of the learning process, and it’s actually a sign that you are making progress and gaining knowledge…

Don’t let ‘imposter syndrome’ stop you – believe in yourself and keep going.

Next time: probably a little bit about masks, unless something drastic changes in the next week...

P.S. In my last post I said that we would need to wait for a randomised trial like the RECOVERY trial in the UK before we could know if hydroxychloroquine actually worked or not. As it turns out, the results from the RECOVERY trial came out the day after I wrote this, and hydroxychloroquine doesn’t work.

4 thoughts on “The reason why bleach can NEVER cure COVID-19

  1. I really loved the Groucho quote, which I had forgotten! You write and explain things very well, Tom.

    Love, Kate


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