Side Effects of the DTaP Vaccine

The DTP vaccine is notorious because it is associated with the most side effects. It is also the vaccine that single-handedly triggered the modern antivaccine movement. With the advent of the newer DTaP vaccine, most of the side effects linked to the older vaccine are much milder and occur with lower frequency.


If my baby developed a fever after the DTaP vaccine, is it safe for him to get the same vaccine in the future? Children who experience these common reactions (fever, loss of appetite, crying) can still receive the DTaP vaccine in the future. Even though similar reactions may occur with future vaccination, they are quite harmless.

The most common side effect is tenderness at the site of injection. This can last for more than three days. In addition, swelling and redness over a large area of the skin where the injection was given can last up to two weeks. Even though these side effects are common, parents tend not to worry much about these reactions because they are so mild and do not have any lasting effect.

Fever is another common side effect, which occurs in approximately 20 to 25 percent of the children receiving this vaccine. Loss of appetite and irritability are also common side effects. Even though these reactions are common, they go away in a few days and do not cause any permanent problems.

Some of the more serious reactions to the DTaP vaccine include seizures and unusually prolonged crying. These reactions have been proven to occur after the administration of the DTaP vaccine, and most experts agree that the vaccine is responsible for these reactions. Fortunately, these reactions rarely occur. Only about 1 in 14,000 children develops seizures, and 1 in 1,000 children may have excessive crying. Even though these reactions are scary and need a thorough medical investigation after they occur, they do not lead to permanent problems with the brain.

The heart of controversy surrounding the DTaP vaccine is that it has been linked to serious but rare problems. In particular, the developments of seizures and swelling in the brain have been implicated with the older DTP vaccine. The biggest controversy is whether the current DTaP vaccine can cause permanent brain damage.


Most of the studies done about the safety of the whooping cough vaccine were based on the older DTP vaccine that is no longer used. Less is known about the current DTaP acellular vaccine, but most experts and doctors agree that the new DTaP vaccine causes significantly less side effects than the old DTP vaccine.

In the 1990s, a flurry of research activities took place to answer this specific question. At the time, only the older whole-cell DTP vaccine was being used. A British study demonstrated that the link between the old DTP vaccine and brain damage is definitely possible, and such reaction could affect 1 in 140,000 children receiving the DTP vaccine. Subsequent studies in Great Britain as well as the United States have put the original British study in doubt. Nevertheless, no study can completely refute any association between the old DTP vaccine and permanent brain damage.

If you are more confused about the relationship between the DTaP vaccine and brain damage after reading this, you are not alone. Even experts cannot agree whether the DTaP vaccine can cause brain damage. One thing that everyone can agree on is that if such a devastating side effect could be caused by the DTaP vaccine, it is extremely rare. Most doctors believe that the frequency of such reaction is on the order of one in a million.

It is probably impossible to ever prove or disprove a causal relationship between the DTaP vaccine and brain damage. The difficulty for such research is that brain damage is so rare. Intuitively, you can imagine that if the DTaP vaccine causes brain damage in a majority of children, there wouldn't be any healthy children by now.


If your child has existing neurologic problems, such as recurrent seizures or severe developmental delay, talk to your pediatrician about the risk of the DTaP vaccine. Certain individuals are more susceptible to seizures triggered by the vaccine. The doctor may decide to postpone the DTaP vaccine or forgo it altogether.

On the other hand, the possibility that DTaP vaccine causes brain damage certainly exists, but there are ways to avoid such reaction. Children with existing brain damage or deteriorating neurological disorders should be exempt from the DTaP vaccine, and children with severe seizures should not receive the DTaP vaccine until their seizures are brought under control.

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