Can I just add lactase to milk? A DIY Guide

October 21, 2025 •

4 min read

According to the National Institute of Diabetes and Digestive and Kidney Diseases, millions of Americans have lactose intolerance, a condition that makes digesting dairy difficult. For those looking for an alternative to store-bought options, the question arises: can I just add lactase to milk? The answer is yes, you can, and it's a simple, cost-effective process that allows you to create your own lactose-reduced dairy products.

Quick Summary

This guide explains how to add lactase drops to milk, the necessary incubation period for effective lactose reduction, and how to safely store your homemade lactose-free milk. Find out how this method works, its benefits, and what to expect regarding taste and consistency. Compare this DIY technique to store-bought alternatives to determine the best option for your needs.

Key Points

Lactase drops can be added to milk to make it lactose-free: Liquid lactase enzyme drops are designed to be mixed directly into milk or other liquid dairy products.
The process requires refrigeration and patience: After adding the drops, the milk must be refrigerated for at least 24 hours to allow the enzyme to break down the lactose.
Homemade lactose-free milk is often more cost-effective: Converting regular milk at home using lactase drops is generally cheaper than buying pre-made lactose-free milk from the store.
Lactose-free milk tastes sweeter: The breakdown of lactose into simple sugars (glucose and galactose) makes the treated milk noticeably sweeter than regular milk.
This method does not work for acidic dairy products: Lactase enzymes are not effective in high-acid environments, so they should not be used for products like yogurt or buttermilk.
Customizable lactose reduction is possible: You can adjust the dosage of lactase drops and the waiting time to control the extent of the lactose reduction.
Consult a healthcare provider before use: While generally safe, it is always wise to consult a doctor before using lactase products, especially for vulnerable populations like infants or pregnant women.

Understanding How Lactase Works

Lactase is an enzyme that naturally breaks down lactose, a complex sugar found in milk and dairy products, into two simpler, more easily digestible sugars: glucose and galactose. For individuals with lactose intolerance, the body produces insufficient amounts of this enzyme, leading to digestive issues when consuming dairy. By adding a liquid lactase enzyme, typically in drop form, to milk, you initiate this same breakdown process outside the body. This pre-digestion step means that when you drink the milk, your body has far less lactose to process, which helps mitigate common symptoms like gas, bloating, and stomach cramps. The treated milk is then essentially lactose-free or significantly lactose-reduced, depending on the dosage and incubation time.

The Simple Steps to DIY Lactose-Free Milk

Making your own lactose-reduced milk at home is a straightforward process that requires minimal effort. Here's a step-by-step guide:

Purchase liquid lactase drops: These are widely available at pharmacies, health food stores, and online retailers.
Measure your milk: Determine the quantity of milk you want to treat, whether it's a single serving or an entire carton. Standard recommendations often suggest a certain number of drops per liter of milk.
Add the drops: Following the product's instructions, add the specified number of lactase drops to your milk. It is important to remember that more drops and a longer incubation time result in a higher level of lactose breakdown.
Mix and refrigerate: Shake or stir the milk thoroughly to ensure the enzyme is evenly distributed. Place the milk back in the refrigerator immediately.
Wait for the conversion: The enzymatic reaction requires time to complete. Most products recommend waiting at least 24 hours in the refrigerator for a significant lactose reduction. For a more complete conversion, some users may opt to wait up to 48 hours.
Test and enjoy: The treated milk will taste slightly sweeter than regular milk because lactose has been broken down into simpler sugars, glucose and galactose. Once the waiting period is over, your homemade lactose-free milk is ready to be used in any application where you would use regular milk.

Important Considerations and Potential Outcomes

While adding lactase drops is highly effective for most liquid dairy products like milk, cream, and formula, it's not suitable for all applications. The enzyme is ineffective in highly acidic environments, so it will not work for making acidic dairy products like yogurt, buttermilk, or sour cream lactose-free. The enzymatic reaction is also temperature-sensitive; adding the drops to milk that is too hot can destroy the enzyme, rendering it useless. It is always best to add drops to refrigerated or room-temperature milk and allow the process to take place in a cool environment.

Homemade vs. Store-Bought Lactose-Free Milk


Feature	DIY Lactose-Free Milk (with drops)	Store-Bought Lactose-Free Milk
Cost	Generally more cost-effective, especially for frequent milk drinkers.	Higher retail price due to processing and packaging costs.
Convenience	Requires planning and an incubation period of at least 24 hours.	Ready-to-drink immediately. Convenient for impulse purchases.
Customization	Allows you to control the level of lactose reduction and sweetness.	Fixed level of lactose reduction determined by the manufacturer.
Flavor	Can have a noticeably sweeter taste due to the sugar breakdown.	Sweeter than regular milk, but taste can vary by brand.
Control	Full control over the source and quality of the milk used.	Dependent on the manufacturer's sourcing and standards.

Conclusion

In conclusion, adding lactase directly to milk is a legitimate and effective method for creating your own lactose-reduced dairy at home. This process empowers individuals with lactose intolerance to enjoy milk without the accompanying digestive discomfort, often at a lower cost than buying pre-treated products. By understanding the process—including the required wait time and the fact that it only works for liquid, non-acidic dairy products—you can successfully customize your milk to your dietary needs. While the process requires some foresight, the benefits of controlling your lactose reduction level and saving money can be significant. Always follow the specific directions on your lactase product and allow for the full incubation period to achieve the best results.

Lactase Drops Instructions: Follow product-specific dosages, as concentrations vary.
Temperature Matters: Add drops to cold or room-temperature milk; heat can destroy the enzyme.
Patience is Key: Allow for an adequate incubation period, typically 24-48 hours, in the refrigerator.
Taste Expectation: Anticipate a slightly sweeter flavor profile in your finished lactose-free milk.
Use with Caution: Lactase drops are not effective for acidic dairy products like yogurt or sour cream.
Safety First: Consult a doctor, especially for infants or pregnant individuals, before using supplements.

Frequently Asked Questions

It typically takes at least 24 hours of refrigeration for lactase drops to effectively break down most of the lactose in milk. A longer incubation period can result in a more complete lactose reduction.

Yes, adding lactase drops will make the milk taste sweeter. This is because the lactase enzyme breaks down lactose into glucose and galactose, which are sweeter-tasting sugars.

No, lactase drops are not suitable for acidic dairy products like yogurt, buttermilk, or sour cream. The lactase enzyme is ineffective in acidic environments.

Yes, you can use lactase powder from capsules by dissolving it in a small amount of water first, then adding the solution to your milk. The liquid drop form is often more convenient for mixing.

Yes, liquid lactase drops can be used to treat baby formula and expressed breast milk. Always consult a healthcare provider or a nutritionist for specific instructions and before starting any new supplement for an infant.

Proper refrigeration is crucial for the enzymatic process and for maintaining the milk's freshness. If left unrefrigerated, the milk could spoil, and the lactose conversion process would be less effective or inconsistent.

No, lactase enzymes are inactivated by high temperatures (above 50 degrees Celsius or 122 degrees Fahrenheit). Always add drops to cold or warm (not hot) milk and allow the conversion to happen in the refrigerator.