Every vaccine comes with a chance of side effects, and the Tdap vaccine is no exception. Fortunately, reported side effects with Tdap are generally mild and go away on their own. Mild to moderate side effects may include: mild pain, redness, or swelling at the shot site; tiredness ; body aches ; headache ; nausea, vomiting, or diarrhea ; fever ; swelling of the entire arm in which the vaccine was given ; Severe problems after the Tdap vaccine are rarely reported, but may include: