Do Vaccines Have Any Side Effects?

All vaccines carry a risk of side effects. Most of these are mild and resolve within a week of administration. Some vaccines are mandatory during childhood; others are optional but advised for certain age groups or health conditions. Some vaccines are given only when exposure to disease is possible or likely, such as those received in anticipation of foreign travel. Vaccines are usually given to cause the body to create antibodies that will fight the disease should exposure occur.

Injection Site Pain

Most vaccines are given by injection into the muscle. The site of an injection may become reddened, warm or swollen. The skin could become thickened for several weeks or a small nodule could develop under the skin. Pain, burning or stinging at the site is also possible. A large area may become sore, such as the entire upper arm.

Fever

Often, the body will respond to a vaccine by producing intermittent fever for up to a week. While usually mild, some vaccines can lead to a high fever in some individuals. Fever may be accompanied by episodes of chilling. Occasionally, a child or adult will have convulsions as a result of this fever.

Flu-like Symptoms

The "2010 Lippincott's Nursing Drug Guide" reports that vaccines may cause a wide variety of flu-like reactions. These include runny nose, stuffy nose, sore throat, reddened or sore eyes, cough, fatigue, headache, muscle aches and joint soreness. Young children may be fretful, fussy or drowsy while older children may complain that they feel "bad." Some of the lymph nodes may be swollen.

Loss of Appetite

Many individuals have a loss of appetite in the days following vaccine administration. Nausea, vomiting and diarrhea are other potential gastrointestinal side effects.

Fainting

The U.S. Centers for Disease Control and Prevention explains that some injected vaccines can cause fainting. This usually happens within the first 15 minutes after injection. Some people will have a seizure when they faint.

Hypersensitive Reactions

Some patients have a hypersensitive or allergic reaction due to a vaccine component. Typical reactions include a rash or itching at the site or over the body. Swelling of the face, lips, mouth, tongue or throat may occur. This type of swelling can become life-threatening as it can impair the ability to breathe.

Unusual Side Effects

Vaccines can cause a variety of unusual reactions. Some of these include swelling of the salivary glands, swelling and pain of the testicles, deafness in one ear, dizziness and facial-area paralysis. A rash may appear that is not due to an allergic response.