Vaccine (Shot) Complications (Side Effects)

Problems with DTaP and Tdap range from mild to severe; the good news is that severe problems (seizures, coma, brain damage, nerve problems, or severe allergic reactions) occur in less than one in 1 million vaccinations. Many investigators think the severe complications are so rare that it is difficult to prove they are actually related to the vaccine administration. Consequently, the vast majority of physicians continue to advocate the use of the vaccines.

The most frequent mild side effects of DTaP are pain, fever, fussiness in children, and redness or swelling at the injection site. About one in four children may show some or all of these effects, and they may be more prevalent after the fourth or fifth dose. Other mild problems (feeling tired, decreased appetite, vomiting, fussiness) may occur one to three days after the shot. Fussiness occurs most frequently (one in three children), followed by tiredness and decreased appetite (one in 10), while vomiting is infrequent (about one in 50). Moderate or uncommon effects of DTaP are a seizure or high fever (105 F or higher); these occur in about one of 14,000 children vaccinated.

The most frequent mild side effects of Tdap are pain, redness, headache, chills, nausea with occasional vomiting or diarrhea, swollen lymph glands, joint pain, and fever of about 100.4 F. Mild side effects occur in about two in three to three in four adolescents and adults while mild fever (100.4 F) may occur in one of 25 adolescents and one of 100 adults. Moderate side effects of Tdap are pain, redness, swelling, nausea, vomiting, diarrhea, and fever of 102 F or higher. Redness, swelling, and pain occur slightly more frequently in adolescents (about one in 16 to 20) than in adults (about one in 25 to 100). A similar frequency is seen with fever and gastrointestinal side effects (about one to three per 100 adolescents) compared with fever in one in 250 adults and gastrointestinal side effects in one in 100 adults.

Most mild side effects of DTaP and Tdap usually require no treatment and are gone within 24 hours; moderate side effects may be treated symptomatically, but a child with a high fever or seizure should be evaluated and possibly treated by a physician. Do not use aspirin to treat children's pain or fever.