Aspartame consumption is not associated with adverse effects in the general population. Studies have found no evidence of an effect of aspartame on a wide range of adverse effects including hypersensitivity reactions, elevated blood methanol or formate levels, hematopoeitic or brain cancers. Neurological changes tested included cognitive functions, seizures, headaches and changes in memory or mood.

Grade I
Overall strength of the available supporting evidence: Grade I - good; Grade II - fair; Grade III - limited; Grade IV - expert opinion; Grade V: not assignable

A limited number of human studies published in peer reviewed journals that involved children or special adult populations were available for this question. 

Limited evidence suggests that aspartame consumption is not associated with detrimental effect on blood methanol, eye problems, acne, blood pressure, seizure disorder, or attention deficit disorder in children.

There is limited evidence for three special population adult groups. In patients with diabetes, aspartame consumption is not associated with elevated plasma phenylalanine and tyrosine levels, fasting glucose control, intolerance to aspartame, opthalmologic effects, heart rhythm or weight. In patients with chronic alcoholic liver disease, portal systemic encephalopathy index was unchanged. Levodopa levels were not significantly different in individuals with Parkinson's disease.

Grade III
Overall strength of the available supporting evidence: Grade I - good; Grade II - fair; Grade III - limited; Grade IV - expert opinion; Grade V: not assignable