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Medically reviewed by Last updated on Apr 5, 2023.

Excipient (pharmacologically inactive substance)

What is it?

Aspartame (C14H18N2O5) is a common sugar-free sweetener known commercially by the brand names of Equal or NutraSweet. It is used in pharmaceutical products, often as a sugar replacement in chewable tablets and sugar-free liquids. The FDA approved the use of aspartame in food products in 1981. It is an artificial sweetener, often consumed as a sugar replacement in various foods and beverages. Chemically, aspartame is a methyl ester of phenylalanine.[1]

The major concern with the use of aspartame is in patients with autosomal recessive phenylketonuria. The by-product of aspartame when it is broken down in the body is phenylalanine. Most people can metabolize the phenylalanine amino acid; however, certain patients with the homozygote genetic predisposition to phenylketonuria, or PKU, with strict dietary restriction should avoid aspartame. The FDA requires that all food or beverage products that contain aspartame have this warning listed on the nutrition label. FDA has reported that aspartame is safe as a general purpose sweetener in food and is not carcinogenic.[2] The European food code for aspartame is E951.

Headache is a commonly reported adverse effect with aspartame. Neuropsychiatric side effects have also been reported with higher doses of aspartame, although these are yet to be confirmed in controlled clinical trials. Chronic use of aspartame may be more likely to trigger headaches. The FDA has documented seizures, and there is evidence they may be associated with aspartame use, although definitive evidence is lacking. Research suggests patients with poorly controlled “absence seizures” should possibly avoid aspartame use.[1] A short-term clinical trial also evaluated the effect of aspartame on cognitive and behavioral performance in children 3 to 10 years of age. The study reported that even when intake exceeds typical dietary levels, neither dietary sucrose (sugar) nor aspartame affects children's behavior or cognitive function.[3]

List of medications using Aspartame


  1. Inactive Ingredients in Pharmaceutical Products: Update. Committee on Drugs Pediatrics 1997;99;268
  2. U.S. FDA. Food. FDA Statement of European Aspartame Study. CFSAN/Office of Food Additive Safety. April 20, 2007. Accessed March 30, 2012. 1
  3. Wolraich ML, Lindgren SD, Stumbo PJ, et al. Effects of diets high in sucrose or aspartame on the behavior and cognitive performance of children. N Engl J Med. 1994;330:301-7.

Further information

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