What to do if a dish is too spicy?

If a dish is, too spicy offer something which is neutral in flavor to temper the spiciness of your meal like pasta, plain rice, bread, etc. 

And another way to cut down the spiciness when you are too heavy-handed with chili peppers is by adding

 Acid:  Depending on the dish try adding some citrus juice like lemon which works best with most flavors, vinegar, chopped pineapples, tomato juice, or sauce.

Veggies: Bulk up with other ingredients to dilute the spiciness.

Carrots or Potatoes: Adding carrots or potatoes, the sugar in them, and the porous texture helps to fight heat and absorb some of the spice.

Nuts: Depending on the dish, try adding some Nuts Paste like peanut or almond butter, cashews nuts paste, or tahini ( sesame seeds paste )

Cool Down With Dairy. Stir in a time yogurt, sour cream, milk, coconut milk, and mild cheese to tempers spice and counteract overly hot flavors.

By adding Sweeteners. Sweet defeats heat by neutralizing the heat of chile peppers. A sprinkle of sugar or honey or a touch of sweet ketchup. If it's a tomato-based sauce, stir in a little more sauce to reduce the spiciness.