Europe's drugs regulator on Friday concluded three new conditions linked to the administration of Johnson & Johnson's COVID-19 vaccine shot.

The European Medicines Agency (EMA) recommended that immune thrombocytopenia, or low blood platelets, dizziness, and tinnitus, or ringing in the ear, be added to the labels of J&J's single-shot vaccine as potential adverse reactions.

Menstrual disorders, however, have not been found causal association with the vaccination, said the EMA, adding it had requested more data from vaccine developers to assess the issue.

It stressed that the benefits of J&J's vaccine still outweighed any risks, adding that it had analyzed 1,183 cases of dizziness and more than 100 cases of tinnitus to reach such a conclusion.

"We strongly support raising awareness of the signs and symptoms of rare events to ensure they can be quickly identified and effectively treated," U.S.-based J&J said in a statement, adding that data on adverse reactions is periodically shared with regulators.

The EMA last month listed a rare nerve-degenerating disorder, Guillain-Barré syndrome (GBS), as a possible rare side-effect from the J&J shot. The company has also struggled with supply in the European Union.

The EMA has also added GBS as a possible side-effect of AstraZeneca's COVID-19 vaccine, and said on Friday it was still monitoring such reports.

Both J&J and AstraZeneca vaccines use similar technology but with different versions of a cold virus to deliver immunity-building instructions to the body.