All medications and vaccines cause side effects, although in some cases these are very mild and might not be apparent. Generally, hepatitis B vaccine side effects are mild and non-threatening, but there are some moderate-to-severe side effects that can occur in rare cases. The hepatitis B vaccine is a recombinant vaccine made from synthetic versions of proteins from the hepatitis B virus. It is not a live or killed virus and therefore cannot cause a hepatitis B infection. This vaccine is safe for almost all people, including infants, children and older people.
The most common hepatitis B vaccine side effects are very mild and are not dangerous. Approximately 25 percent of people who have the vaccine will experience some soreness at the site of injection. About one out of every 15 people will have a temperature of 99.9 degrees Fahrenheit (37.7 degrees Celsius) or higher.
There are many other possible hepatitis B vaccine side effects, most of which are rare or non-threatening. Respiratory side effects that might occur include cough, rhinitis, upper respiratory tract infection, flu-like symptoms and asthma-like symptoms. Visual disturbances, joint and muscle pain or stiffness, swollen lymph nodes and mild allergic reactions can occur. Abnormal liver function tests are an uncommon side effect; more serious liver problems such as cancer or liver disease are not reported side effects.
Severe allergic reaction to the hepatitis B vaccine is extremely rare, occurring at a frequency of approximately one in 1.1 million. The symptoms of allergic hepatitis B vaccine side effects include hives or a rash, tightness in the chest, difficulty breathing and swelling of the face, lips, tongue or mouth. If someone who has had the hepatitis B vaccine experiences these side effects, he or she should seek emergency medical attention immediately.
Other potentially severe hepatitis B vaccine side effects include nervous system, cardiovascular and immunological side effects. Cardiovascular side effects include low blood pressure, fainting, heart palpitations and rapid heartbeat. The immune system can be affected by the autoimmune disease systemic lupus erythematosus, or vasculitis, in which blood vessels near the infection site become inflamed.
There are several possible nervous system side effects that can occur after the use of the hepatitis B vaccine. Temporary mild symptoms include headache, vertigo, dizziness, insomnia and sleepiness. Convulsions and inflammatory nervous system diseases such as encephalitis and myelitis are other possible consequences. People with multiple sclerosis might experience worsening of their symptoms after hepatitis B vaccination.