De hyppigste bivirkninger ved Herceptin (der ses hos mere end 1 ud af 10 patienter) er abdominale smerter (mavesmerter), asteni (svækkelse), brystsmerter, kulderystelser, feber, hovedpine, smerter, diarré, kvalme, opkastning, artralgi (ledsmerter), myalgi (muskelsmerter) og hududslæt.
The most common side effects with Herceptin (seen in more than 1 patient in 10) are abdominal (tummy) pain, asthenia (weakness), chest pain, chills, fever, headache, pain, diarrhoea, nausea (feeling sick), vomiting, arthralgia (joint pain), myalgia (muscle pain) and skin rashes.