Hypersensitivity (allergic) reactions can occur with Esperoct and are uncommon (affecting up to 1 in 100 people). These include swelling, burning and stinging at the injection site, chills, flushing, itchy rash, headache, hives, low blood pressure, lethargy, nausea and vomiting, restlessness, a rapid heartbeat, tightness of the chest, tingling and wheezing. In some cases these reactions can become severe.

Very rarely, patients may develop antibodies against hamster protein in the medicine and have allergic reactions. Esperoct must not be used in patients with allergy to hamster proteins.

Following treatment with factor VIII products, including Esperoct, some patients may develop inhibitors (antibodies) against factor VIII, causing the medicine to stop working and resulting in a loss of bleeding control. In such cases, a specialised haemophilia centre should be contacted.

For the full list of side effects and restrictions with Esperoct, see the package leaflet.