Drug Levels and Effects:

Summary of Use during Lactation:

Aspartame is not detectable in breastmilk after maternal ingestion because it is rapidly broken down in the mother's body. An extremelylargeintake of aspartame (equivalent to 17 cans of soda or 100 packets of Equal Sweetener) can slightly increase the amount of phenylalanine in breastmilk. Phenylalanine concentrations in milk return to baseline by 12 hours after alargesingle dose of aspartame. Although it is prudent to avoid the use of aspartame in women who are nursing an infant with phenylketonuria, amounts that are typically ingested in aspartame-sweetened foods and beverages do not result in any additional risk to breastfed infants with phenylketonuria.

Drug Levels:

Aspartame is rapidly metabolized in the body to 2 amino acids that occur naturally in breastmilk, aspartic acid and phenylalanine.

Maternal Levels.

Six lactating women an average of 98 days postpartum (range 42 to 159 days) were given aspartame or lactose orally in a dose of 50 mg/kg (equivalent to 17 aspartame-sweetened sodas or 100 packets of Equal in a 68 kg [150 lb] adult[1]) on 2 separate occasions 2 weeks apart in a randomized crossover trial. Breastmilk samples were collected over the next 24 hours. Breastmilk phenylalanine levels increased to a maximum of about 6 mg/L between 1 and 8 hours after the dose of aspartame and returned to baseline by about 12 hours after the dose. Lactose had no effect on breastmilk phenylalanine levels. Aspartame was not detected (<1.4 mg/L) in breastmilk at any time. The authors calculated that if the milk phenylalanine concentration were elevated for 24 hours to the maximum found in this study, a fully breastfed infant would receive an additional 0.5 mg/kg daily above the normal intake of 79 mg/kg of phenylalanine that occurs naturally in breastmilk.[2]

Infant Levels.

Relevant published information was not found as of the revision date.

Effects in Breastfed Infants:

Relevant published information was not found as of the revision date.

Possible Effects on Lactation:

Relevant published information was not found as of the revision date.

Alternate Drugs to Consider:



1. Franz M. Is it safe to consume aspartame during pregnancy? A review. Nutrition update. Diabetes Educ. 1986;12:145-7. PMID:3634700
2. Stegink LD, Filer LJ Jr, Baker GL. Plasma, erythrocyte and human milk levels of free amino acids in lactating women administered aspartame or lactose. J Nutr. 1979;109:2173-81. PMID:512705

Substance Identification:

Substance Name:


CAS Registry Number:


Drug Class:

  • Artificial Sweeteners

  • Sweetening Agents

  • Administrative Information:

    LactMed Record Number:


    Last Revision Date:

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