There are two main reasons why using a mouse regularly can be hazardous.

First, using a mouse requires a person to make small, exact movements with their hand, fingers, and thumb. By positioning, travelling, scrolling, and clicking the mouse again and again, the same small muscles can become tired and overworked. This overuse can cause:

Pain (ache, soreness) on the top of the hand (Figure 1)

Pain (ache, soreness) around the wrist (Figure 1)

Pain (ache, soreness) along the forearm and elbow (Figure 1)

Formulation of painful nodules, and in the later stages, ganglion cysts, around the joints and along the tendons

Numbness and tingling in the thumb and index finger

Burning, stiffness, restricted range of motion



Figure 1 Figure 1

The second reason using a computer mouse can be hazardous is that the placement of the mouse can make it awkward to reach. Many computer workstations have limited space; since the keyboard is already directly in front of the person using the computer, most times the mouse is placed around the upper right (or left) hand corner of the keyboard and toward the back of the desk (Figure 2).



Figure 2 Figure 2

When the mouse is in this position (Figure 2), it is out of 'easy reach': it is beyond the safe distance range for comfortable hand movements. In order to use the mouse, the person has to lean forward, reaching outwards and forwards (Figure 3) and remain there unsupported for as long as they are using the mouse.



Figure 3 Figure 3

Maintaining this position for the workday can cause soreness and fatigue by putting an extra load on the muscles in the upper back (trapezius muscle) and shoulder (deltoid muscle). Repeated use of the mouse, therefore, can cause aches and pains in the shoulder and neck area. Lower back pain, while not directly caused by the mouse, can also be a problem if the computer user has poor posture and leans forward when they sit.