Subtle to imperceptible. SAG is an "insurance-tier" antioxidant — most users report nothing acute. Reported effects in user communities (when not stacked with anything else):

• Mild reduction in post-exertion fatigue or hangover-like inflammation symptoms after a few weeks of consistent use.
• Possible subjective "lighter" feeling in users with measured GSH deficiency or chronic illness (Long COVID, chronic infection, heavy metal exposure).
• No cognitive sharpening, no euphoria, no acute "feel."
• Some users report nothing at all over months of use.

The user base most likely to report a subjective benefit is people with diagnosed GSH deficiency, autoimmune conditions, chronic fatigue, or post-viral syndromes — populations where the antioxidant baseline is plausibly impaired. In healthy 20-year-olds with adequate dietary cysteine + already-supplemented NAC, subjective effect is expected to be near-zero.

Onset to felt benefit (where any): typically 2-4 weeks of daily dosing. No acute effect.

• Tolerance buildup: none expected. Mechanism is substrate replacement, not receptor-mediated; cells use GSH continuously and turnover is rapid (intracellular GSH half-life is hours, not days).
• Recommended cycle: None. Daily-safe at 100-300 mg.
• Reset protocol: N/A.

Synergistic with

• n-acetyl-cysteine (NAC): Complementary in theory — NAC supplies upstream cysteine substrate; SAG supplies downstream intact GSH delivered to cells. However, this stack is largely redundant for healthy adults — both are working on the same intracellular GSH pool, and cysteine is rate-limiting in most contexts, so adding SAG on top of NAC produces diminishing returns. Worth considering only in measured GSH deficiency.
• astaxanthin: Different antioxidant niche (lipid-soluble, mitochondrial membrane). Combines with SAG (water-soluble cytoplasmic) for layered ROS coverage. Both daily-safe in V5 plan.
• alcar: Mitochondrial-energy + antioxidant pairing. ALCAR provides acetyl groups + carnitine for fatty-acid β-oxidation; SAG protects mitochondrial GSH pool from peroxide damage. Theoretical synergy; light empirical data.
• alpha-lipoic acid (ALA): Recycles oxidized GSH (GSSG) back to reduced GSH. Common functional-medicine stack pairing.
• vitamin C: GSH and ascorbate cycle each other in the antioxidant network. V4 already includes 500 mg vitamin C.

Avoid stacking with

• Chemotherapy agents (cisplatin, doxorubicin, etc.): Theoretical antagonism by reducing tumor oxidative stress. Not relevant for Dylan; flagged for completeness.
• Pre-existing high-dose NAC + liposomal GSH + SAG triple-stack: Redundant and expensive; pick one delivery form per goal.

Neutral / safe co-administration

• All V4 stack components: NAC, citicoline, magnesium glycinate + threonate, DHA, PS, curcumin, rhodiola, theanine, glycine, D3+K2, beta-alanine, vitamin C, creatine.
• All V5 planned additions: modafinil, bromantane, Adamax/Semax, ALCAR, apigenin, astaxanthin, l-tryptophan, taurine.

• CYP enzymes: Glutathione is a Phase II detox substrate (GST enzyme family conjugates GSH with electrophiles for excretion); SAG raises intracellular GSH, which can theoretically accelerate Phase II conjugation and reduce circulating exposure of drugs that depend on GST-mediated metabolism. No clinically significant drug-level interactions reported.
• Acetaminophen/paracetamol overdose context: GSH and NAC are mechanistic antidotes — GSH is the protective conjugate that prevents NAPQI hepatotoxicity. SAG would theoretically protect against acetaminophen toxicity but NAC is the established clinical antidote, not SAG.
• Chemotherapy: As above, theoretical antagonism with oxidative-stress-dependent agents.
• Contraceptives: No documented interaction.

The most relevant SNPs for endogenous glutathione capacity:

• GSTM1 / GSTT1 / GSTP1 polymorphisms — glutathione-S-transferase enzyme variants. GSTM1-null homozygotes (~50% of Caucasians) have reduced GSH-conjugation capacity and may benefit more from GSH-supporting interventions. GSTT1-null is a similar risk allele. 23andMe coverage: these are reported in raw data (rs1065411, rs17856199, rs4147581 area) but not in the standard health reports — would need a third-party tool (Nutrahacker, SelfDecode, Genetic Genie) to interpret.
• GCLC / GCLM polymorphisms — glutamate-cysteine ligase catalytic and modifier subunits, the rate-limiting enzyme for GSH synthesis. Reduced-function variants (GCLC -129 C>T, GCLM -588 C>T) lower endogenous GSH capacity. Less commonly reported in 23andMe but checkable.
• NRF2 (NFE2L2) variants — master transcriptional regulator of the glutathione synthesis pathway. Variants affecting NRF2 activation (rs6721961, rs35652124) modulate baseline GSH capacity.
• Practical for Dylan: Once 23andMe results land (~June 5-15, 2026), specifically check GSTM1-null status. If null + persistent oxidative-stress markers on bloodwork → SAG (or liposomal GSH) becomes a reasonable add. If GSTM1-positive and bloodwork clean → SAG remains skip-tier.

If reconsidered, the most evidence-backed option for Dylan would be Tri-Fortify liposomal (peripheral GSH coverage with the strongest published bioavailability data within the OTC stabilized-GSH category) — $67/mo. Plain SAG is cheaper ($25-35/mo) but has weaker bioavailability data than liposomal in head-to-head comparators.

• Baseline (before starting): Whole-blood reduced glutathione (GSH) and oxidized glutathione (GSSG); GSH/GSSG ratio (specialty lab — Genova, Doctor's Data, ZRT). Plasma 8-OHdG (DNA oxidative damage marker). F2-isoprostanes (lipid peroxidation marker). hsCRP. ALT/AST. GSTM1 / GSTT1 / GCLC / GCLM genotype if available.
• During use: Repeat whole-blood GSH and GSH/GSSG at 8-12 weeks. ALT/AST at 12 weeks (no expected hepatotoxicity but standard tracking).
• Post-cycle (if cycled): N/A — not cycled. If discontinuing, recheck GSH/GSSG at 4-8 weeks to confirm baseline drift.
• Subjective: No reliable subjective marker — this is biomarker-driven decision-making, not feel-driven.