After a meeting of its Pharmacovigilance Risk Assessment Committee (PRAC), the drug regulator said on Friday that venous thromboembolism, a potentially life-threatening blood clotting condition, should be added to the J&J vaccine’s product label as a rare possible side effect. The illness causes a clot to form in the vein of a leg, arm, or the groin, which can then travel to the lungs and cut off the blood supply.

Alongside the blood clotting concern, the EMA warned that immune thrombocytopenia, a disorder that causes the body to mistakenly attack its own blood platelets, should be added to the drug’s potential side effects. It also recommended adding it as a possible adverse reaction to AstraZeneca’s Covid vaccine.

This is not the first time that J&J has been advised to add a blood clotting risk as a potential side effect, with the PRAC previously highlighting the potential link between the company’s vaccine and cerebral venous sinus thrombosis, as well as splanchnic vein thrombosis – clots that target the brain and the abdomen respectively.

The EMA did not announce any change to its previous risk assessment of the J&J vaccine, which stated that the positives outweigh the potential risks, giving European nations the green light to use the jab.

Responding to the EMA’s updates on Friday, J&J said that it would update its product information accordingly, while noting that the chances of such conditions are very low.