Antipyretics ‘reduce covid immunity, help fight TB’

3 minute read

Pain and fever drugs have been around so long, we’ve neglected to see what else they can do.

Pain and fever medications, the most widely used drugs on the planet, can have opposite effects on the immune system in response to different infections such as covid and TB, according to research published today in the British Journal of Clinical Pharmacology. 

A clinical review of studies examining NSAIDs, paracetamol and opioid analgesics on infectious diseases found that in some cases they showed promise as cheaply available antiviral treatments while at other times they reduced an immune response. 

When it comes to covid, it appears to be the latter.  

Lead author Dr Christina Abdel-Shaheed told The Medical Republic that studies had found a “blunted immune response” to covid vaccine after taking NSAIDs. But the clinical implications of those reductions were still largely unclear. 

“If someone experiences a fever or headache that warrants treatment after they’ve had a vaccination, they can be used therapeutically without issue,” she said. “But it’s certainly not recommended to take them as prophylactic treatment to try to prevent those events. It should really be reserved for treatment and, ideally, treatment in moderate-to-severe cases, as opposed to mild.” 

Studies also suggested that the effect of NSAIDs on immune response lasted six to eight hours and was most pronounced after the first vaccine. 

Dr Abdel-Shaheed said the impact of these drugs on immunity was an important consideration when treating children and immunocompromised people. 

“There are unanswered questions about the clinical implications of using these drugs immediately after vaccinations,” she said. 

“The theoretical risk is that if it does blunt the immune system, it could increase the risk of infection and alter the effectiveness of the vaccine, but that hasn’t been demonstrated in clinical trials.” 

An unexpected finding was that opioids including morphine, fentanyl and oxycodone, widely used in post-surgical and critical care, supressed key immune cells, affecting innate immunity. This effect was dose dependent. 

“Whether we need to think about analgesic alternatives to morphine in those settings is something that really warrants further exploration,” she said. 

This was also relevant to opioid withdrawal, explained Dr Abdel-Shaheed. 

“Stopping suddenly can also impact the immune system, so it really should be done slowly.” 

On the plus side, there are early signs that indomethacin, an anti-inflammatory drug commonly used to relieve arthritis pain, can reduce the need for oxygenation and pulmonary complications in people with covid when used in addition to standard care. Clinical trials are needed to investigate further. 

And in TB, the humble aspirin has been shown in clinical trials to reduce the burden of infection, and the risk of stroke and death in some cases by around 10%. 

“Drug-resistant TB is becoming a major public health threat. TB is the second-biggest killer among the infectious diseases directly after covid-19 – 1.5 million people died from TB in 2020,” Dr Abedel-Shaheed said. 

 “We’re not immune to having an outbreak of TB here in Australia. And if this disease keeps becoming resistant to the best current treatments, potentially we face a major clinical health crisis.” 

In low-income countries, where TB has the greatest impact, anti-microbials can be hard to access. 

“Something as simple and low cost as aspirin, combined with existing therapies, can provide a timely and effective solution to this. I think it needs to be explored further.” 

British Journal of Clinical Pharmacology, online 1 March 2022 

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