Takeaways
• No credible evidence of systemic toxicity
Large epidemiologic and clinical data sets show no association with autism, neurologic outcomes, allergic disease, or autoimmune disease.
• Exposure is small and efficiently cleared
Cumulative exposure remains below thresholds considered toxic, and intramuscular dosing results in slow release and renal elimination.
• Local reactions are the primary adverse events
Aluminum-adjuvanted vaccines have a long safety record with mainly transient injection-site reactions and no evidence of systemic effects.
A recent review published in Pediatrics evaluated the use of aluminum adjuvants in childhood vaccines and examined evidence related to proposed long-term toxicities and developmental, neurologic, allergic, or autoimmune outcomes. The authors noted that aluminum salts have been used in vaccines for nearly a century and remain the most widely used adjuvants in pediatric immunization. They wrote that “aluminum salts have consistently been demonstrated over nearly a century of use to enhance the immune responses elicited by vaccines while also being well-tolerated by nearly all who take them.”1
Aluminum salts are included in vaccines to enhance antibody responses and to support the durability of protection, particularly for subunit vaccines. The review described that adjuvants “enable dose-sparing (fewer doses and lower antigen content)” and allow subunit antigens to generate immunity that would not otherwise occur. According to the authors, adjuvants remain especially important in early infancy when immunologic responses may be less robust.
How do aluminum adjuvants function in childhood vaccines?
The review summarized the role of aluminum adjuvants in supporting the magnitude and duration of vaccine effectiveness. The authors noted that “adjuvants are needed because purified subunits lack microbial nucleic acids or cell-wall components that engage innate immunity,” which can otherwise limit immunogenicity.
What does current evidence show about aluminum exposure and systemic toxicity?
The review addressed concerns about aluminum exposure from the routine pediatric schedule. The authors noted that “the cumulative exposure to aluminum contributed by the entire current American Academy of Pediatrics (AAP) childhood immunization schedule (through age 18 years…ranges from 4.12–7.52 mg.”2
Pharmacokinetic data cited in the report demonstrate slow absorption from the injection site and renal clearance. The authors wrote that “aluminum salts form a depot at the injection site and dissolve slowly over several months,” which prevents systemic accumulation. In addition, serum studies have not demonstrated clinically meaningful elevations following vaccination. The review described that even in preterm infants, “no rise in serum aluminum levels could be detected 24 hours following vaccination.”
Is aluminum in vaccines associated with autism or neurodevelopmental disorders?
The review examined epidemiologic data regarding autism spectrum disorder (ASD). The authors stated that converging evidence indicates autism originates prenatally, and that “postnatal exposures are unlikely causes.” Several large-scale studies showed no association between aluminum-adjuvanted vaccines and ASD. They wrote that the results “indicate that neither vaccine-derived nor other postnatal aluminum exposures increase ASD risk.”
Do aluminum-adjuvanted vaccines increase asthma or allergic disease risk?
Regarding allergic disease, the report noted that aluminum salts can induce IgE responses to contained antigens, but available evidence does not support sensitization to unrelated allergens. Observational studies evaluating asthma risk have yielded inconsistent signals, but the authors stated that “the association weakened when children were compared in more closely matched groups.”
In contrast, larger Danish and German cohorts showed no increased risk of allergic disease or asthma following vaccination.
Is there evidence linking aluminum adjuvants to autoimmune disease?
Autoimmune outcomes were also reviewed, including the proposed entity autoimmune/inflammatory syndrome induced by adjuvants (ASIA). The authors noted that ASIA “has not been substantiated by high-quality human evidence,” and is not recognized by allergy or immunology professional societies.
The review described macrophagic myofasciitis (MMF) as a histologic finding at prior injection sites but reported that evidence does not support an association with systemic disease. The authors stated that lesions occur in “healthy individuals as well as those reporting symptoms.”
How should clinicians counsel caregivers about aluminum adjuvants?
The review included practical communication points for clinicians addressing caregiver questions. The authors emphasized the importance of acknowledging concerns and providing clear data, explaining that “communication that validates concerns while providing accurate information is most effective in reducing caregiver anxiety and maintaining vaccine confidence and uptake.”
They noted that strong clinician recommendations remain a major factor in vaccination acceptance.
Conclusion
According to the review, aluminum salts remain essential components of many pediatric vaccines and substantially contribute to immunogenicity and disease prevention. The authors concluded that “the evidence strongly supports the safety of aluminum adjuvants and their necessity in certain vaccines,” citing no convincing evidence of toxicologic, autoimmune, developmental, or neurologic associations in contemporary data.
References
- Nirenberg E, Maldonado YA, Hoffman SA. The Role and Safety of Aluminum Adjuvants in Childhood Vaccines. PEDIATRICS. Published online December 3, 2025. doi:https://doi.org/10.1542/peds.2025-074874
- American Academy of Pediatrics. AAP-Immunization-Schedule. Published online September 17, 2025. https://downloads.aap.org/AAP/PDF/AAP-Immunization-Schedule.pdf
