Appendicitis occurs on the right side, not the left.

As part of our body, the appendix can become inflamed and painful if we are not careful. Appendicitis is especially painful and can significantly impair daily life and work. Since appendicitis has many potential causes, a common question arises: “Does appendicitis occur on the left or right side?”

Left or Right Side of Appendicitis?

Patients with appendicitis typically experience pain on the right side. Under normal circumstances, the appendix is located in the lower right abdomen. Its standard anatomical position lies at the outer one-third of the line connecting the umbilicus to the right anterior superior iliac spine. However, due to individual variations during embryonic development, the appendix may occasionally lie outside this region. For example, in “mirror-image” individuals (situs inversus) or when the appendix lies beneath the liver, atypical positioning may occur—though these are rare exceptions. In most people, the appendix resides in the lower right abdomen; thus, appendicitis usually presents as lower right abdominal pain. Medically, this characteristic pattern is termed “migratory right lower quadrant pain”: the pain may not initially localize to the lower right abdomen but instead begin as vague upper abdominal discomfort. This early, poorly localized pain results from visceral nerve reflexes triggered by inflammation.

The appendix is primarily situated in the lower right abdomen and the right iliac fossa; therefore, for the vast majority of individuals, acute appendicitis manifests as lower right abdominal pain. Nevertheless, mirror-image patients are exceedingly rare in clinical practice. In such cases—termed situs inversus—*all* internal organs are mirrored relative to their normal positions: organs normally on the right appear on the left, and vice versa. Consequently, in mirror-image individuals, the appendix resides on the left side, potentially causing lower left abdominal pain.

Patients should drink plenty of water in daily life and seek prompt, active medical treatment. We hope this information proves helpful to you.