**Core Concept**
Tri cyclic antidepressants (TCAs) are a class of medications used to treat depression, anxiety disorders, and certain types of chronic pain. They work by inhibiting the reuptake of norepinephrine, serotonin, and sometimes dopamine, thereby increasing the levels of these neurotransmitters in the synaptic cleft.

**Why the Correct Answer is Right**
TCAs have a range of side effects due to their mechanism of action and pharmacological properties. These include anticholinergic effects (e.g., dry mouth, constipation), orthostatic hypotension, weight gain, and sedation. Some TCAs also have significant cardiovascular side effects, such as QRS prolongation and QT interval prolongation, which can increase the risk of serious cardiac arrhythmias.

**Why Each Wrong Option is Incorrect**
**Option A:** Not a side effect of TCAs. This option is correct because TCAs are known to cause a range of side effects, but "increased appetite" is not typically listed among them.
**Option B:** This is a side effect of TCAs. TCAs can cause significant weight gain, which is a common complaint among patients taking these medications.
**Option C:** This is a side effect of TCAs. TCAs have anticholinergic effects, which can lead to dry mouth, constipation, and other gastrointestinal symptoms.
**Option D:** This is a side effect of TCAs. TCAs can cause sedation, which can be a significant problem for some patients.

**Clinical Pearl / High-Yield Fact**
It's essential to monitor patients taking TCAs for signs of cardiovascular side effects, such as QRS prolongation and QT interval prolongation, which can increase the risk of serious cardiac arrhythmias.

**Correct Answer:** A. Increased appetite.