Also known as: aluminum salts, Adju-Phos
Aluminum Phosphate
Sourced from FDA-approved package inserts (DailyMed). Last verified: 2026-07-07.
What It Is & Why It's in Vaccines
Aluminum phosphate is an aluminum salt adjuvant chemically distinct from aluminum hydroxide, with different surface charge and antigen-adsorption properties. Different products use different aluminum salts depending on the antigen's isoelectric point and the desired adsorption/desorption kinetics.
Same mechanistic role as aluminum hydroxide (§aluminum-hydroxide). Aluminum phosphate has a different isoelectric point (~4.5–5.0 vs ~11 for aluminum hydroxide), making it more suitable for adsorbing antigens that are negatively charged at physiologic pH.
Dose-in-Context
Per-Dose Quantity
0.125–0.85 mg aluminum per dose (FDA limit: ≤0.85 mg/dose, 21 CFR 610.15). Some products combine aluminum hydroxide and aluminum phosphate.
Reference Comparison
See aluminum hydroxide entry for the Mitkus et al. (2011) pharmacokinetic model — the same aluminum body-burden framework applies regardless of the specific aluminum salt form, since systemic aluminum exposure is determined by total elemental aluminum content, not the salt species.
Source: Mitkus RJ et al. Vaccine. 2011;29(51):9538-9543.
Route-of-Administration Note
Same route-of-administration considerations as aluminum hydroxide.
Documented Adverse Effects
Same local reactogenicity profile as aluminum hydroxide — injection-site pain, erythema, swelling, nodule formation.
Subcutaneous nodules/granulomas at injection site, particularly after subcutaneous administration.
Same neurodevelopmental safety evidence base as aluminum hydroxide — no causal association found between aluminum adjuvants (of either salt type) and neurodevelopmental outcomes in multiple large-scale reviews.
Same MMF finding caveats as aluminum hydroxide. The French MMF case series included both aluminum hydroxide and aluminum phosphate vaccine sites.
Vaccines Containing Aluminum Phosphate
DTaP/Tdap — Daptacel (Sanofi Pasteur)
PCV (Pneumococcal) — Prevnar 20 (Pfizer Inc.)
ⓘ Methodology Disclaimer: Ingredient lists are sourced from official FDA-approved package inserts for the specific branded products named on each vaccine page. Formulations can change between manufacturing lots and over time — always verify against the current package insert before making a clinical decision. The presence of a substance in a vaccine does not by itself indicate harm; toxicology is dose-, route-, and context-dependent. Comparisons to reference exposure levels are provided with their sources where available, and are approximate — see the cited source for full methodology.