If I take the pill alysena (Alesse), someone told me that with the COVID-19 vaccine I have a greater chance of getting thrombosis. Is this true?

In the general population, the risk of thrombosis/phlebitis is about 4-5 per 10,000 women per year. When taking a pill such as Alysena containing estrogen and progestin, there is a slight increase in the risk, but it remains very low. The incidence would be about 9-10 cases per 10,000 women per year. In comparison, the risk of thrombosis after childbirth is 300-400 cases/ 10,000 women per year.

So, yes, by taking the pill, your risk of thrombosis is slightly higher than a woman who does not take it. This risk, which is considered to be very low, is mainly present during the first few months of use. It is also greater if, for example, you are very overweight, smoke or are over 35 years old. Therefore, any woman taking the pill should be aware of the signs of thrombosis (sudden onset of pain/swelling/redness in a leg or sudden difficulty in breathing) and consult a doctor promptly if this occurs.

However, your risk of getting a thrombosis after the COVID vaccine is no greater than any other. In fact, it is important to remember that thrombosis associated with vaccination is a kind of immune reaction, which is unrelated to those that occur in other circumstances. Also, at your age, you will be receiving Pfizer or Moderna.

We look forward to hearing from you,

Sarah-Yan Chagnon, pharmacist