Common anti-inflammatory drugs may leave body open to viral attacks, study suggests

A new study says some anti-inflammatory drugs could allow viruses to spread more easily. (Credit: Pexels)

Some medications used to treat autoimmune diseases may also make viral infections worse, new research suggests.

A study from the Norwegian University of Science and Technology (NTNU) found that Janus kinase (JAK) inhibitors — a class of anti-inflammatory drugs — can suppress a key part of the immune response, potentially allowing viruses like influenza and COVID-19 to replicate and spread more easily.

JAK inhibitors are used globally for conditions like rheumatoid arthritis, psoriatic arthritis, ulcerative colitis and atopic dermatitis.

The researchers say these drugs block an important immune response known as Type I interferon (IFN) signalling, which helps infected cells sound the alarm to neighbouring cells, slowing viral spread and giving the body time to mount a broader defence.

In a video interview with CTVNews.ca on Monday, NTNU researcher and study co-author Denis Kaynov compared the body’s layered immune response to a race with hurdles.

“These inhibitors remove the first line of hurdles — our innate immune defences — allowing viruses to run faster,” he said. “Without that early delay, the adaptive immune system doesn’t have time to respond properly, which increases the risk that the virus spreads rapidly from cell to cell and organ to organ.”

The researchers used a range of human cell types, including lung, eye and brain cells. Kaynov says the team later moved to organoids — simplified lab-grown mini-organs — to mimic the behaviour of full organs more accurately.

While JAK inhibitors are effective in controlling chronic inflammatory conditions, Kaynov says they may leave patients vulnerable if they become infected with a virus.

“If you’re on this kind of medication and get an infection like the flu, the virus could spread much more easily in the body,” he said. “It’s important to consult your physician if you suspect an infection while taking these drugs.”

Although the research remains in early stages, one infectious diseases specialist says the findings are worth noting.

“This is very, very early on in the pipeline,” Isaac Bogoch said in an interview with CTVNews.ca last week. “It’s pre-clinical research, which is extremely important and needs to be done, but also just the first step.”

Bogoch says the broader risks of JAK inhibitors are already well known.

“They’re not like taking acetaminophen,” he said. “There’s a well-established link to higher susceptibility to infections — especially bacterial ones — so it’s not entirely surprising that viral vulnerability is also being investigated.”

Bogoch emphasized that while the research doesn’t call for immediate clinical changes, it does raise useful questions about drug safety, especially for older adults or patients with multiple health conditions.

Despite the concerns, the NTNU team sees potential upsides. In highly controlled lab environments, the same drug effects that make the body more vulnerable could be used to researchers’ advantage — for example, to help manufacture viral materials for vaccines or cancer therapy.

Kaynov says clinical trials aren’t on the horizon — “it would potentially kill a lot of people,” he noted — but the lab results could influence how doctors advise patients during active outbreaks.

If someone becomes sick while taking JAK inhibitors, Kaynov says they should contact a doctor to assess whether to pause the medication or consider alternatives.

“It really depends on the virus,” he said. “Some kill in hours or days. Others linger. But the timing of the immune response is critical either way.”