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Generic name: lactaseLAK-tase ]
Brand names: Lactaid, Lactaid Fast Act, Lactaid Ultra, Lac-Dose, Lactrase, Surelac
Drug class: Digestive enzymes

Medically reviewed by on Dec 21, 2023. Written by Cerner Multum.

What is Lactrase?

Lactrase is an enzyme that helps your body break down lactose in dairy products. If you are lactose-intolerant, consuming a dairy product can cause gas, bloating, stomach pain, or diarrhea.

Lactrase is a dietary supplement that can help prevent these symptoms in people with lactose intolerance who consume milk or other dairy products.

It is not certain whether Lactrase is effective in treating any medical condition. Medicinal use of this product has not been approved by the FDA. This medicine should not be used in place of medication prescribed for you by your doctor.

Lactrase is often sold as a dietary supplement. There are no regulated manufacturing standards in place for supplements and some marketed products have been found to be contaminated with toxic metals or other drugs. Dietary supplements should be purchased from a reliable source to minimize the risk of contamination.

Lactrase may also be used for purposes not listed in this product guide.

Lactrase side effects

Get emergency medical help if you have signs of an allergic reaction: hives; difficult breathing; swelling of your face, lips, tongue, or throat.

Less serious side effects may be more likely, and you may have none at all.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.


Follow all directions on the label and package. Use exactly as directed.

Before taking this medicine

This product may contain phenylalanine and could be harmful if you have phenylketonuria (PKU).

Ask a doctor, pharmacist, or other healthcare provider if it is safe for you to use this product if you have other medical conditions.

Do not give Lactrase to a child younger than 4 years old.

Ask a doctor before using this product if you are pregnant or breastfeeding.

How should I take Lactrase?

When considering the use of a supplement, seek the advice of your doctor. You may also consider consulting a practitioner who is trained in the use of herbal/health supplements.

If you choose to use Lactrase, use it as directed on the package or as directed by your doctor, pharmacist, or other healthcare provider. Do not use more of this product than is recommended on the label.

Take Lactrase with the first bite or sip of any dairy product you consume. You may take this medicine daily with every meal and snack that contains dairy.

If you consume more dairy products after 30 to 45 minutes, take Lactrase again.

Call your doctor if you still have symptoms of lactose intolerance or if your symptoms get worse while using this product.

Store at room temperature away from moisture and heat. Do not refrigerate.

What happens if I miss a dose?

Take your dose as soon as you can at the beginning of a meal or snack. Do not take two doses at one time.

What happens if I overdose?

An overdose of Lactrase is unlikely to cause serious symptoms.

What should I avoid while taking lactase?

Avoid taking your dose too early or too late in relation to a meal that contains dairy, or Lactrase could be less effective.

What other drugs will affect Lactrase?

Other drugs may affect Lactrase, including prescription and over-the-counter medicines, vitamins, and herbal products. Tell your doctor about all other medicines you use.

Further information

Remember, keep this and all other medicines out of the reach of children, never share your medicines with others, and use this medication only for the indication prescribed.

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.