OnTriggerEnter

I need some help with onTriggerEnter, I want to be able to have attack the enemy (with Input.GetMouseButtonDown(0) and also need to have to have a collision with the ShortSword game object, but it is not working! I want my enemy to loose health if he gets touched by the ShortSword and mousebutton is down. Also I am working in 2D. thx for the help :)

 using UnityEngine;
 using System.Collections;
 
 public class Enemy : MonoBehaviour {
     public float Health = 100;
     public GameObject ShortSword;
     // Use this for initialization
     void Start () {
     
     }
 
 
 
     // Update is called once per frame
     void Update () {
         if(Input.GetMouseButtonDown(0) && OnTriggerEnter(ShortSword))
         {
             Health=Health - 10;
             Debug.Log(Health);
         }
     }
 }