Common drugs can help viruses spread

Medications are supposed to help us get rid of disease, or at least alleviate the symptoms. 

That's why it's especially unfortunate when medications instead may contribute to making us sicker. Many medications can have side effects, but some are particularly serious.

“We have found a surprising and potentially serious side effect of a class of anti-inflammatory drugs. They can help viruses spread more easily in the body,” says Denis Kainov.

He is a professor at NTNU's Department of Clinical and Molecular Medicine.

Some viruses spread more easily

The drugs that can make the body more vulnerable to viral infections are widely used. They are known as Janus kinase inhibitors, or JAKs.

“Among the viruses that more easily affect the body with the help of these drugs are Rift Valley fever virus, influenza A, adenovirus, and SARS-CoV-2, the virus that causes Covid-19,” says Kainov.

These are both serious and common viral infections that can be bad enough without the inadvertent help of medications.

Medications used for autoimmune diseases and arthritis

In a new scientific article, Kainov and colleagues describe how these drugs can promote viral infections.

“JAK inhibitors are often prescribed for autoimmune diseases and inflammatory conditions such as rheumatoid arthritis,” says Erlend Ravlo. He is a researcher at NTNU.

But they also weaken the body’s natural defences against viruses.

“In particular, the drugs suppress an important immune signalling pathway that helps protect healthy cells from viral attacks,” he says.

Inhibits important gene response against viruses

The researchers found that drugs such as baricitinib slow down the genes that respond to viral infections.

“These genes play a crucial role in the body’s response to viral infections,” says Aleksandr Ianevski. He is also a researcher at NTNU.

By stopping or slowing down this signalling pathway, JAK inhibitors remove the body’s antiviral shield. This allows viruses to more easily gain a foothold and spread.

The researchers discovered this using  advanced techniques. They examined cells from the lungs, eyes, and brain. They also studied laboratory-created mini-organs.

“Although JAK inhibitors are effective in the treatment of inflammation, this shows that they can pose a hidden risk for patients who have latent or active viral infections,” says Ravlo.

Can be useful to know during the development of medications

The findings suggest that healthcare professionals should be cautious when prescribing JAK inhibitors, especially during viral outbreaks.

But the researchers point out that this immunosuppressive effect may also be useful in controlled environments, such as in the development of vaccines or screening of antiviral drugs.

The researchers hope to increase awareness among doctors and researchers about the effects of these drugs.

“We recommend further studies to better understand how the drugs can be used optimally, especially during virus outbreaks or pandemics,” says Ianevski.

Reference: 

Ravlo et al. JAK inhibitors remove innate immune barriers facilitating viral propagation, NAR Molecular Medicine, vol. 2, 2025. DOI: 10.1093/narmme/ugaf017

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