Common (>10%):

• Paresthesia at single doses ≥1.6 g. Harmless, fades 60-90 min. Dose-split or use SR to eliminate.
• Mild GI discomfort at doses >3 g in a single serving — usually resolves with split-dosing.

Uncommon (1-10%):

• Mild flushing in addition to paresthesia in some users — likely a histamine-adjacent response in a small subset.
• Transient sleep disruption if a large dose is taken close to bedtime in a sensitive user — uncommon.

Rare-serious: None established at supplemental doses. Reviewed systematically by ISSN 2015 and by a 2019 meta-analysis on β-alanine risk assessment (PMC6520041). No serum biomarker changes, no organ-specific safety signals at doses up to 6 g/day for 8+ weeks of human trials.

Theoretical concerns (mostly debunked in humans):

• Taurine depletion — β-alanine and taurine share the Tau-T (SLC6A6) and PAT-1 (SLC36A1) transporters. Rodent studies at very high relative doses (≥3% in drinking water) show muscle taurine reductions and downstream effects (one rat study reported retinal nerve fibre layer changes — Murakami 2019 PMID 31473259). In humans at standard supplemental doses, muscle taurine concentration does not measurably decline in the available data. The risk-assessment meta-analysis (2019) concluded no clinical taurine concern. Some cautious practitioners still add 1-3 g/day taurine as a hedge; the evidence base does not require it.
• Histidine depletion — never observed in real human supplementation; histidine intake from a mixed Western diet vastly exceeds the substrate demand of muscle carnosine synthesis. Only a theoretical concern in severe protein restriction.

Watch periods (Dylan-specific):

• First 2 weeks of loading: tingle adaptation. If paresthesia is genuinely intolerable, switch to SR or drop per-dose to 0.8 g × 6/day.
• Weeks 6-8 of loading: confirm the late-round subjective benefit is showing up. If completely absent at 8 weeks of consistent dosing, you're either a non-responder, your training stimulus isn't in the buffering-relevant range, or compliance has been imperfect.
• Weight-cut window: make sure GI tolerance holds at lower calorie intake; sometimes a 1.6 g dose hits harder on an empty stomach.

WADA / drug testing: β-alanine is not on the WADA Prohibited List and is unrestricted in all major combat-sport sanctioning bodies including USADA, UFC's PED program (drug-tested division), ONE Championship's drug-testing program, ABC commissions, and amateur MMA / IBJJF. Safe for any tested athlete.