If your child is found to be intolerant of the proteins gluten and casein, chances are you have implemented a gluten-free, casein free diet (GFCF) to help him or her overcome the symptoms of ADHD.
The diet seems easy enough - simply eliminate all dairy products and wheat-based foods from the diet.
But did you know that there are non-dairy and non-wheat foods that serve as hidden sources of gluten and casein? There are a number of foods that may use milk or wheat ingredients, but that unfortunately do not warn consumers of their gluten or casein content.
To prevent your child from accidentally eating these foods, look carefully at ingredients lists and avoid foods that contain any one of the following: Gluten

• Wheat
• Rye
• Barley
• Oats.
  Although oats by themselves do not contain gluten, they are often processed along with gluten-containing grains and may be contaminated.
  Because it is difficult to say for sure, it's best to avoid oats entirely.
  
• Pasta
• Bread
• Pancakes
• Crackers
• All baked goods
• Granola bars
• Cocoa
• Soy sauce
• Luncheon meats

The following ingredients also serve as hidden sources of gluten.
Watch out for them.

• Barley malt
• Baking powder
• Bouillon cubes
• Binders
• Fillers
• Extenders
• HPP (hydrolyzed plant protein)
• HVP (hydrolyzed vegetable protein)
• TVP (texturized vegetable protein)
• Malto-dextrose or malt
• MSG (monosodium glutamate)
• Modified food starch
• Seasonings
• Baker's yeast
• Vegetable gum
• Some food starches

Casein All dairy products contain casein, including the following:

• All forms of animal milk, be they skim, low-fat, evaporated, or condensed
• Yogurt
• All cheeses
• Butter
• Ice cream
• Milk chocolate

Dairy products are the most obvious sources of casein, but milk is an ingredient in many non-dairy preparations.
The following food items are known to contain casein as well as gluten.

• Canned soup
• Bread crumbs
• Bottled salad dressings
• Soy cheese
• Chewing gum
• Breath mints
• Protein shakes
• Processed meats and sausages
• Wine

Read the ingredients label carefully and avoid foods with the following casein-containing ingredients:

• Milk solids
• Whey
• Caseinate
• Sodium caseinate
• Caseinogen
• Lactose
• Hydrolyzed vegetable protein

Non-food items Cosmetics, some medicines, and many other non-food items may contain inedible gluten.
In fact, many of these items are used around the house on a daily basis! They include

• Stamps and envelopes (the sticky part)
• Multivitamins
• Many prescription and over-the-counter medications
• Some herbal supplements
• Lip products like lip balm, ChapStick, lip gloss, or lipstick

Cross-contamination Watch out for cross-contamination, or situations where foods with casein or gluten may accidentally come into contact with gluten-free or casein-free foods, or with the utensils your child uses.
For instance, you use a knife to butter your toast, then give it to your child to use without washing it.
The best way to avoid cross-contamination is to have the whole family go on the GFCF diet.
This will keep your child from being alienated from the rest of the family and the foods he or she enjoys, and it may end up treating unknown food intolerances in other family members.