The most common side effects with Jcovden are usually mild or moderate and get better within 1 or 2 days after vaccination. 

The most common side effects are pain at the injection site, tiredness, headache, muscle pain and nausea. They may affect more than 1 in 10 people. 

Fever, chills, as well as redness and swelling at injection site may affect up to 1 in 10 people. Dizziness, shaking, coughing, mouth and throat pain, sneezing, diarrhoea, vomiting, rash, joint pain, muscle weakness, backache, pain in the arms and legs, weakness and feeling generally unwell may affect up to 1 in 100 people. Rare side effects (which may affect up to 1 in 1,000 people) are lymphadenopathy (enlarged lymph nodes), itchy rash, hypersensitivity (allergy), paraesthesia (unusual sensations like numbness, tingling or pins and needles), hypoesthesia (reduced sensation to touch, pain and temperature), facial paralysis, tinnitus (ringing or buzzing in the ears), venous thromboembolism (formation of blood clots in veins) and sweating. 

For booster vaccinations, the number and severity of reactions tended to be higher when people had previously been vaccinated with a vaccine other than Jcovden compared to people who completed a primary course with Jcovden. 

Thrombosis (formation of blood clots in the blood vessels) in combination with thrombocytopenia (low levels of blood platelets), known as TTS (thrombosis with thrombocytopenia syndrome), and Guillain-Barré syndrome (a neurological disorder in which the body’s immune system damages nerve cells) may affect up to 1 in 10,000 people. 
Allergic reactions, including anaphylaxis (severe allergic reaction), have occurred in people receiving the vaccine. As for all vaccines, Jcovden should be given under close supervision with appropriate medical treatment available. 

A very small number of cases of immune thrombocytopenia (a condition in which the immune system mistakenly targets blood platelets, reducing their levels and affecting normal blood clotting), capillary leak syndrome (fluid leakage from small blood vessels causing tissue swelling and a drop in blood pressure), cutaneous small vessel vasculitis (inflammation of blood vessels in the skin) and transverse myelitis (a neurological condition characterised by an inflammation in the spinal cord) have occurred with Jcovden. 

Jcovden must not be given to people who have previously had capillary leak syndrome; it must also not be given to people who have had TTS following vaccination with any COVID-19 vaccine.