All VAERS reports use symptoms from the MedDRA symptom classification system. The MedDRA is organized at five levels of detail: System Organ Class High-Level Group Terms High-Level Terms Preferred Terms Lower Level Terms Although the full MedDRA is proprietary information, a partial listing is shown here which includes only those terms that are found in VAERS reports. Note that the full MedDRA has 70,177 LLT symptoms, but VAERS uses only 8,507 (12%). You can search this MedDRA hierarchy by typing one or more words here and clicking 'Find'. It will show a new window with those symptoms that match all of the words.