How do i make a sword only do damage to an enemy when the left mouse button is clicked?

I have a script that whenever the enemy is collided with the sword, it takes 10 damage from the enemy. The problem is that the enemy takes damage just by the character walking into the enemy. I want it so that the enemy can only take damage from the sword when the left mouse button is clicked. How should I do this? This is my code so far:

var enemyHealth : int;

function Start () {
	enemyHealth = 100;
}

function OnTriggerEnter(coll : Collider) {
	if(coll.gameObject.tag == "Sword"){
			enemyHealth = enemyHealth-10;
			Debug.Log("Enemy Hit with Sword and health is" + enemyHealth);
		}
	
}

function Update () {
	if(enemyHealth <= 0)
	{
		Destroy(GameObject.FindWithTag("enemy"));
		Debug.Log("Enemy Died");
	}
}

function OnTriggerEnter(coll : Collider) {
if(coll.gameObject.tag == “Sword” && Input.GetKeyDown(KeyCode.Mouse0)){
enemyHealth = enemyHealth-10;
Debug.Log(“Enemy Hit with Sword and health is” + enemyHealth);
}