(CNN) If the idea of drinking hand sanitizer, absorbing ultraviolet light and gargling salt water to prevent or treat Covid-19 sounds bizarre to you, know that this isn't the first time humans have put themselves in dangerous situations to quell their fears.
In the face of threat by a new infectious disease, people become desperate, said Dr. Jeremy Brown, an emergency care physician and author of "Influenza: The Hundred-Year Hunt to Cure the Deadliest Disease in History."
That desperation and a similar threat were what made people living during the 1918 flu pandemic — which killed 50 million to 100 million people worldwide — flock to dangerous quack treatments like moths to flames. That included doctors.
Although conventional doctors had just recently gained more respect than alternative practitioners by the early 20th century, mainstream doctors still "had almost nothing to offer" for the flu said Laura Spinney, a science journalist and author of "Pale Rider: The Spanish Flu of 1918 and How It Changed the World."
Since they thought the 1918 flu was a bacterial disease instead of a virus, their knowledge and treatment efforts fell short, she said.
"Through the course of the pandemic, you see people gradually turning away from conventional medicine as they realize it can't help and turning to the alternatives, folk medicines, quack cures and so on," Spinney said. "Which, of course, until very recently (in the early 20th century), had been equally respectable and equally accessible."
Doctors also "really had no concept of when a medicine becomes a poison — how medicines interact with human tissues and what the right dosing is," Spinney added. Those questions are what "we ask in our clinical trials these days that cost so much, take so long and try to measure safety and efficacy."
Additionally, during the Covid-19 pandemic, "we've talked a lot ... about the importance of trust between people and doctors and public health experts," Spinney said. "But trust also mediates the kind of intimate relationship between a patient and their physician. And it shapes, in a strong way, that placebo effect and hence the effectiveness of any treatment.
"One of the interesting things you see in 1918 is that trust broken down because people saw that their doctors were hopeless. And so they, seeking to control the symptoms, turned to alternative systems which they felt could offer more hope, more effective treatments at that point," she added.
"In different ways, both these pandemics have illustrated to us how absolutely critical to so many aspects of health care — not least, whether people participate in vaccination campaigns — comes down in the end to trust and trust the general public has in their medics and in their governments."
Devastation, desperation and an inexperienced, unregulated medical field constituted a petri dish for numerous unproven — and sometimes barbaric — treatments.
Aspirin, made from the bark of willow trees, had been used to treat pain for millennia. Since aspirin was known for reducing fevers, too, the drug became the international first-line treatment for flu — sometimes administered in doses six times higher than what is now known to be safe, Brown said.
The problem was misunderstanding that aspirin has a "narrow therapeutic window, meaning if you give too little it doesn't work (but if) you give too much, it can cause some very, very dangerous conditions." They include "sweating, ringing in the ears, rapid breathing and then brain swelling and coma, convulsions and death," Brown said.
Given the exorbitant doses and fatal side effects, many flu deaths may have been from aspirin overdoses rather than just the virus itself, some studies have suggested.
However, some countries with death tolls in the millions — such as India — didn't have easy access to aspirin — so it probably didn't have a major impact on the global death toll, according to one study, Spinney said.
Quinine, another centuries-old drug from cinchona bark, has been used mainly for treating malaria, caused by infection with the parasite Plasmodium. Like the flu, a symptom of malaria is fever.
"If you have malaria, you give somebody quinine, you attack the parasite," Brown said. "If you don't understand that the fever goes away because the parasite is killed by the quinine, you miss out that little step and say the fever went away because the quinine, so quinine must be good for all fevers."
Quinine wasn't toxic to the flu virus since the infective agent that caused flu — a virus — differed from the infective agent that induces malaria — a parasite. That modern medicine will test therapies for similar symptoms is reasonable and common, Brown said. "The problem is if you just take a drug used for one condition and you're not testing it to see if it improves a second condition, but you're just simply giving it on the belief that it must, should or will," he added.
That's the story of the suggestion that hydroxychloroquine can treat Covid-19 symptoms, Brown added — another antimalarial drug that was once touted by US President Donald Trump and temporarily issued an emergency use authorization by the US Food and Drug Administration.
"At the beginning, the question was perfectly reasonable: Does this drug help in this condition?" Brown said. "You don't start with the statement 'it will help' without undergoing ... all the slow and methodical ways in which we test drugs. There are a lot of drugs that we thought would help and had horrible side effects or unknown effects that we haven't bothered to test them."
For more than 2,500 years, medical practitioners had surgically removed blood from patients to blindly treat disease. Partly based on the Greek philosophy of four humors — black bile, phlegm, yellow bile and blood — as the basis of emotions, temperament and health, bloodletting was believed to remedy disease caused by imbalanced humors.
"Some people were hooked on to the belief that even if you were well, having some blood removed was sort of a good preventative measure, like, perhaps today, we might take some vitamins or go on a jog," Brown said.
In the 19th century, doctors used bloodletting to treat fevers, headaches and difficulty breathing. In 1918, "having observed that some patients seemed to take a turn for the better following a gushing nosebleed, menstruation, even — traumatically — miscarriage," Spinney wrote in her book, "some revived the ancient practice of bloodletting."
The trust in and respect for this historical method meant that many practitioners, including top-tier military doctors, swore by bloodletting after others considered it useless.
Some British parents took their sick children to the local gasworks to sit and inhale fumes to reduce their flu symptoms.
A sanitary worker who went to investigate this claim "saw that there was indeed a relationship that while a lot of people were dying of influenza in the local area, at these gasworks where people were working, their influenza rate was much, much lower than the general population," Brown said. "This led people to this observation that inhaling the chlorine gas would be good for you."
Though chlorine is an effective disinfectant that, in high doses, can kill bacteria and viruses, it is also poisonous. Why parents started taking their kids to gasworks before their ideas were substantiated might have started with growing rumors, Brown said.
"Evacuating the bad stuff out of the patient" was the mindset of doctors who treated their patients' fevers with castor oil, enemas and laxatives made from magnesia or mercury chloride, Brown said.
"There was this belief that an enema would be good for you regardless, really, of what your specific disease was," he added. "We have medical textbooks that were published as late as 1913 (or) 1914, in which laxatives were recommended as a treatment for the fevers that accompanied influenza."
Since Western medicine hadn't yet fully spread through Eastern countries such as China and India, some relied on their ancient, traditional forms of healing.
"Witch doctors in the hills of India moulded human figures out of flour and water and waved them over the sick to lure out the evil spirits," Spinney wrote in her book. "In China, besides parading the figures of dragon kings through their towns, people went to public baths to sweat out the evil winds, smoked opium and took yin qiao san — a powdered mix of honeysuckle and forsythia that had been developed under the Qing (dynasty) for 'winter sickness.'"
Generations of local cultures and traditions shaped the remedies people sought to alleviate their symptoms. "Human beings, in general, need to feel a sense of control over whatever is afflicting them. That's just a perennial truth," Spinney said.
Back in 1918, there was no widely available flu vaccine (1940s), no US Centers for Disease Control and Prevention (1946), no World Health Organization (1948) and no polio vaccine (1954).
Doctors and the general public know a lot more than they did in 1918 — so while doctors in 1918 didn't know any better, "we can't claim ignorance" about this pandemic, Brown said.
"People need to take the time to investigate what it exactly is that they're going to use and to only take medications that have been approved by our regulatory authorities (and) prescribed by physicians," he added.
"We don't need to be ignorant about the side effects and the fact that some of these drugs are completely useless."