Hep B Shot Side Effects

Hepatitis B virus (HBV) is an infection that causes chronic liver disease, which may lead to cirrhosis and even liver cancer. It is transmitted through body fluids, and because HBV may not have symptoms in early stages, the most accurate number of afflicted people is unknown. Since the widespread use of a hepatitis B vaccine was implemented in 1990, estimated annual occurrences of HBV have decreased, for example, to less than 50,000 in 2007. Although the hepatitis B vaccine has been successful at reducing HBV in the population, many people are concerned about possible side effects from the vaccine.

Local Injection Site Reactions

Hepatitis B vaccine is injected into a muscle, and mild injection site reactions are common side effects that occur in approximately 25 percent of recipients, according to the Centers for Disease Control and Prevention. Some examples include soreness, swelling and redness at the injection site.

Systemic Reactions

Some reactions that may occur in the body include headache, dizziness, short-term flu-like symptoms or unwell feeling and a low-grade fever. These reactions are less common; for example, fever may occur in less than 7 percent of people, according to the CDC.

Allergic Reaction

People who are allergic to yeast may react to hepatitis B vaccine, because it is a type of vaccine that is derived from yeast cultures. It is also possible to be allergic to other components of the vaccine, although the risk is estimated as less than 1 in 1 million. Symptoms of an allergy include wheezing, hives, hoarseness and changing heartbeat or dizziness.