However, anemia itself has many possible causes.

Iron deficiency—especially when unexplained in an adult—should therefore be investigated rather than automatically attributed to diet or aging.

7. A Feeling That the Bowel Hasn't Fully Emptied

Another symptom that deserves attention is the persistent sensation that you still need to have a bowel movement even after you've already gone.

This feeling is sometimes called tenesmus.

It can occur for many reasons, including inflammation, infections, hemorrhoids, inflammatory bowel disease, and other gastrointestinal problems.

In some circumstances, it can also occur with colorectal tumors.

Again, the symptom alone does not diagnose cancer. But if it continues or is accompanied by bleeding or other bowel changes, it should be evaluated.

8. Iron-Deficiency Anemia With No Obvious Cause

Anemia isn't something you can usually identify simply by looking at yourself.

A blood test is required.

But symptoms can include:

Unusual tiredness

Weakness

Pale skin

Shortness of breath

Headaches

Dizziness

In some adults, unexplained iron-deficiency anemia can result from chronic blood loss in the gastrointestinal tract.