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What is the 3 day rule for baby food?

The 3 day rule for baby food refers to the recommendation that parents introduce new foods to their baby one at a time, waiting 3 days between each new food. This allows parents to monitor for any signs of an allergic reaction or intolerance before introducing another new food. The 3 day rule applies to when you first start introducing solid foods, typically around 6 months of age, and helps reduce the likelihood of developing food allergies and sensitivities.

When to start solid foods

Most pediatricians recommend starting solid foods around 6 months of age. There are several signs that your baby may be ready for solids at this time:

  • They can sit up with support and hold their head steady
  • They appear eager and interested when you are eating
  • They can pick up food and bring it to their mouth
  • They’ve doubled their birth weight

It’s important not to start solids too early, before 4-6 months, as a baby’s digestive system is still immature. Waiting until around 6 months provides crucial nutrients from breastmilk or formula.

Introducing foods slowly

When first introducing solids, go slowly with each new food. Start with just a taste, 1-2 teaspoons, once a day. Gradually increase to 2-3 tablespoons over a week as your baby adjusts. Here are some tips for starting solids:

  • Choose single-ingredient foods at first like avocado, bananas, oatmeal
  • Offer the new food when your baby is alert and hungry
  • Let your baby explore and touch the food first
  • Introduce one new food at a time
  • Wait 3 days before introducing another new food

Why 3 days?

Waiting 3 days between new foods allows time to check for any signs of an allergic reaction or food intolerance. Allergies occur when the immune system overreacts to a food protein. Food intolerances occur when the body has difficulty digesting something. Here are symptoms to look out for after introducing a new food:

  • Rash, redness, swelling of skin
  • Vomiting, diarrhea
  • Congestion, runny nose
  • Gassiness, abdominal pain
  • Fussiness, difficulty sleeping

If you notice any concerning symptoms, stop giving the new food right away. The symptoms should go away once the food is out of their system. By only giving one new food every 3 days, you can pinpoint which food caused the reaction.

Common food allergens

The foods most likely to cause allergic reactions are:

  • Cow’s milk
  • Eggs
  • Peanuts
  • Tree nuts
  • Soy
  • Wheat
  • Fish
  • Shellfish

These foods are typically introduced last, after 6-12 months once other single foods have been established. Some pediatricians may recommend introducing common allergens even later, closer to 1 year old.

3 day food introduction schedule

Here is an example schedule for introducing foods using the 3 day rule:

Day 1 Rice cereal
Day 4 Banana
Day 7 Sweet potato
Day 10 Applesauce
Day 13 Avocado

Continue gradually introducing new foods every 3-4 days. Avoid introducing more than one new food at a time. Be patient and go at your baby’s pace when introducing solids.

Foods to introduce early

Here are some good first foods to start with around 6 months using the 3 day rule:

  • Rice cereal
  • Oatmeal
  • Bananas
  • Applesauce
  • Avocado
  • Sweet potatoes
  • Pears
  • Butternut squash

These single-ingredient foods are unlikely to cause an allergic reaction. Fruits and vegetables can be introduced in any order. Vary textures from purees to mashed to small pieces as your baby develops.

Avoid added sugars and salt

When introducing solids, avoid added sugars, salts, and unhealthy fats. Choose unsweetened yogurt over fruit yogurt. Make your own purees instead of jarred baby food. Homemade allows you to control ingredients.

Here are some tips for making healthy homemade purees:

  • Use a blender or food processor
  • Add water or breastmilk to reach desired consistency
  • Try mixing vegetables into fruit purees
  • Store in an ice cube tray for individual portions

How long to follow the 3 day rule

Follow the 3 day rule as you first introduce solid foods from 6 months to around 8 months old. After your baby has tried a variety of single ingredient foods, you can begin mixing foods together. Here are some combo ideas once your baby has tried the ingredients separately:

  • Applesauce and rice cereal
  • Bananas and avocado
  • Sweet potato and pear
  • Butternut squash and carrots

From 8-10 months, you can gradually introduce more variety and combinations. But continue to be on the lookout for any signs of reactions to new foods.

Introducing common food allergens

Use extra caution when introducing foods more likely to cause allergies. Here are some guidelines:

  • Wait until baby is at least 6 months old
  • Consult pediatrician if there are allergy risks
  • Introduce one allergen at a time
  • Wait 5-7 days between new allergens
  • Watch closely for any reaction

The most common allergens like cow’s milk, eggs, peanuts should be given several days apart. Stop immediately if any concerning symptoms develop and talk to your pediatrician.

Introducing foods after 1 year

After your baby turns 1 year old, the 3 day rule is no longer necessary. At this point, their digestive system has matured and allergen exposure can help develop tolerance. You can begin introducing a wider variety of foods and combinations including:

  • Scrambled eggs
  • Yogurt
  • Peanut butter
  • Tofu
  • Citrus fruits
  • Berries

Your baby’s diet should include a variety of foods for balanced nutrition. Their food preferences and tolerance will continue developing over time.


The 3 day rule provides a safe approach to introducing solids and minimizing allergy risks. Waiting 3 days between new foods allows you to pinpoint reactions and avoid multiple exposures at once. Follow the rule as you first start solids around 6 months old. Then gradually transition to more combinations and textures while remaining observant. Talk to your pediatrician if you have any concerns. With patience and caution, your baby will work up to an adventurous eater!