Acute (single 1-3 g dose): None. Lysine is a clinically silent supplement — no felt onset, no subjective stimulation/sedation/mood effect, no perceptual signature. You take it and notice nothing. This is part of why community reports (dopamine.club aggregate) attributing "energy," "focus," "sleep quality" effects to lysine are probably mis-attributed (other-stack interaction or placebo) — there is no pharmacological basis for an acute psychotropic effect.

Chronic (weeks-months daily use): Still no felt effect. The endpoint is what doesn't happen — fewer cold sores, faster outbreak resolution. Users with recurrent HSV report subjective benefit measured in outbreak counts per year (e.g., 4-6 → 1-3) and outbreak duration (e.g., 10-14 days → 5-8 days). Users without HSV history report nothing.

During an active outbreak (3 g/day loading):

• Hours 0-24: No felt change.
• Days 1-3: Prodromal tingling/itching may subside earlier than usual; lesion progression may halt at vesicle stage rather than full crust.
• Days 3-7: Faster crusting and re-epithelialization vs. untreated outbreaks. Subjective pain reduction.

Variability: Some users describe the antiviral effect as "the difference between a 7-day outbreak and a 3-day outbreak"; others note no meaningful difference. Probable explanation: trigger-dependent. Lysine works best for stress/UV/illness-triggered outbreaks, less for hormonal or trauma-triggered. Baseline arginine intake also matters — a high-arginine meal pattern (nuts, chocolate, gelatin) during prodrome can defeat the antagonism.

Side-effect subjective profile: Nothing at 1 g/day. Mild GI looseness or cramping in some users at 3 g/day, especially if taken on empty stomach. The dopamine.club community report of "digestive-upset" (15 mentions) is consistent with high-dose powder use.

• Tolerance: None — lysine is a metabolic substrate, not a receptor ligand. There is no pharmacodynamic adaptation. The arginine antagonism works on day 1 the same way it works on day 365.
• Cycling: Not necessary. Continuous daily use is appropriate. Some clinicians taper from 3 g → 1 g after 6-12 weeks of outbreak suppression simply because outbreak risk seasonality changes.
• Discontinuation: Abrupt cessation is fine — no rebound, no withdrawal. The only "rebound" is the underlying HSV outbreak rate returning to baseline within weeks.

Synergistic with

• Zinc (15-30 mg/day): Independent antiviral mechanism (interferes with HSV polymerase; topical zinc has direct lesion-healing evidence). The "lysine + zinc" pairing is the strongest non-Rx HSV stack. Watch zinc-copper balance at chronic >30 mg zinc — add 1-2 mg copper after 8 weeks.
• Vitamin C (500 mg-1 g/day): Collagen + epithelial repair cofactor; rate-limits prolyl/lysyl hydroxylation for re-epithelialization. Pair with lysine for lesion-healing emphasis.
• L-arginine restriction (dietary, not supplemental): Functionally synergistic — you're engineering the lysine:arginine ratio. Drop nuts, chocolate, gelatin, raisins during outbreak phase.
• Valacyclovir / acyclovir (Rx): Different mechanisms (Rx = viral DNA polymerase chain termination; lysine = arginine substrate antagonism). Stack additively. Valacyclovir is the higher-leverage option; lysine is a cheap risk-reduction add-on.
• Vitamin D3 (already in V4): Indirect — immune-modulation supports HSV-control axis.
• Lemon balm (Melissa officinalis) topical: B-tier evidence for HSV-1 lesion treatment; pairs with oral lysine.

Avoid stacking with

• L-arginine supplements (citrulline malate, AAKG, supplemental arginine). Directly opposing mechanism. If you're using arginine/citrulline for the pump/NO pathway in training (an MMA athlete might), separate by 6+ hours from lysine and accept the trade-off — or pick one goal.
• Collagen peptides at training-stack doses (10-20 g): Collagen is arginine + glycine + proline heavy; a 10 g collagen peptides dose delivers ~800 mg arginine plus 700 mg glycine. During HSV outbreak phase, this defeats the lysine ratio. Outside outbreak phase, not a concern.
• Gelatin / bone broth (cup+ daily): Same logic — high arginine load.
• High-dose nut consumption (>30 g almonds, walnuts, peanuts): ~1 g arginine per 30 g nuts. Acceptable in maintenance phase, problematic during outbreak phase.

Neutral / safe co-administration

• All V4 stack items (Mg, NAC, citicoline, PS, DHA, curcumin, rhodiola, theanine, glycine, D3/K2, beta-alanine, vitamin C, creatine).
• Most peptides Dylan is using/planning (BPC-157, TB-500, Selank, Adamax) — no interaction.
• Modafinil, caffeine, nicotine — no interaction.
• Carnitine supplements (l-carnitine tartrate, ALCAR) — independent mechanisms; lysine does not raise carnitine downstream of dietary supply saturation.

Pharmacokinetic profile: Lysine is absorbed via SLC7A1/SLC7A14 cationic amino acid transporters (shared with arginine, ornithine, histidine) in the small intestine. Distribution is whole-body amino acid pool. Excretion is ~50% via renal filtration with active reabsorption; remainder is catabolized to acetyl-CoA. No hepatic CYP metabolism — lysine is metabolically inert from a drug-interaction standpoint.

Clinically relevant interactions:

1. Aminoglycoside antibiotics (gentamicin, tobramycin, amikacin, neomycin, streptomycin): Theoretical and animal-data risk of additive renal cortical accumulation + tubular injury. Hold lysine during IV aminoglycoside courses.

2. Calcium supplements: Lysine enhances calcium absorption (Civitelli 1992). Generally a feature, not a bug — but in chronic stone-formers, the increased uptake could shift stone-formation risk if urinary calcium also rises. Monitor 24-hr urinary calcium if stone history.

3. L-arginine, L-citrulline, AAKG, NO-pathway supplements: Pharmacodynamic competition at SLC7A1 transporter. Co-administration reduces effective intracellular concentration of both. Separate by 6+ hours or pick one.

4. Hormonal contraceptives: No interaction. Hepatic CYP-neutral.

5. Anticoagulants (warfarin, apixaban, rivaroxaban): No interaction.

6. Antiseizure drugs (gabapentin, pregabalin, levetiracetam): No interaction.

7. SSRIs / SNRIs: No interaction. The dopamine.club community-data "serotonin syndrome" topic (3 mentions, "warning" severity) is mechanistically implausible for lysine alone and likely reflects stacked-supplement confusion (lysine + tryptophan + 5-HTP + SSRI combinations). Listed for completeness; not a genuine lysine interaction.

8. Levodopa / Sinemet: Theoretical large-neutral-amino-acid competition at the BBB transporter. Practically negligible at supplemental lysine doses; relevant only if megadosing with concurrent Parkinson's treatment.

9. Insulin / oral antidiabetics: Minor effect — high lysine doses can transiently raise insulin (amino acid-induced incretin response). Not clinically meaningful for non-diabetics.

10. Modafinil, amphetamines, lisdexamfetamine: No direct interaction. (The dopamine.club Discord excerpt referencing "lysine metabolite cleaved" from lisdexamfetamine — vyvanse — is correct: vyvanse is a lysine-amphetamine prodrug that requires red-blood-cell-mediated cleavage of the lysine moiety to release dextroamphetamine. Supplemental lysine does not affect vyvanse pharmacokinetics.)

Limited actionable PGx for lysine response. Lysine is an amino acid substrate, not a receptor-target drug — variation in metabolic processing exists but doesn't translate to clinically actionable dosing decisions for the indications above.

• SLC7A1 (CAT-1) variants: Implicated in lysinuric protein intolerance (rare autosomal recessive disease, SLC7A7 mutations). Heterozygote carriers (uncommon) may have altered lysine handling; not screened by 23andMe.
• AASS (α-aminoadipic semialdehyde synthase, lysine catabolic enzyme) variants: Implicated in hyperlysinemia (mostly benign). 23andMe does not flag.
• HSV susceptibility loci: UNC93B1, TLR3, TICAM1, IRF7 variants linked to HSV encephalitis susceptibility (severe disease); not relevant to outpatient cold-sore management.
• Practical PGx interpretation for Dylan: When 23andMe data arrives June 2026, no lysine-specific variant calls are expected to alter the verdict. The PGx surface for lysine is unusually thin.

For Dylan specifically: if he ever decides to trial (e.g., post-grappling-camp cold sore appears): NOW Foods L-Lysine 1000 mg, 250 caps, ~$15 via iHerb is the no-thought option. 1 cap/day prophylaxis is 8 months supply. Bump to 3 caps/day for 6-12 weeks if outbreak; otherwise sit on the bottle.

Quality flags: L-lysine is a commodity amino acid produced at industrial scale (mostly via Corynebacterium glutamicum fermentation) — purity is rarely an issue. Avoid only no-name Amazon brands with no third-party verification. Stick with NSF or USP-verified brands if competing in tested federations.

Sourcing-difficulty rating: easy. No Rx, no gray market, no international shipping needed. Available at every grocery store with a vitamin aisle.

Baseline (only if starting chronic >2 g/day or troubleshooting HSV frequency):

• Plasma lysine (free amino acid panel, 2nd-tier lab). Reference range ~125-260 nmol/mL fasting. Target >165 nmol/mL during HSV prophylaxis per Thein 1984 threshold. Most users on 1 g supplemental hit this; on 3 g, comfortably exceed.
• Plasma arginine — for the ratio context. Free AA panel typically reports both. Target lysine:arginine plasma ratio >1.0 during outbreak suppression.
• HSV-1 / HSV-2 IgG/IgM titers — useful to confirm seropositive status if outbreaks are atypical or undiagnosed. IgG = past infection / chronic carrier; IgM = active or recent. Not required for routine cold-sore management (clinical diagnosis suffices).
• 24-hr urinary calcium — only if chronic >3 g/day + nephrolithiasis history.
• Serum albumin — proxy for protein nutrition status; relevant only if dietary protein is low.

During use:

• Outbreak diary: Frequency per quarter, duration in days, severity 1-10. Most useful biomarker for HSV efficacy assessment.
• GI tolerance subjective: Stool consistency, cramping. Adjust dose if persistent.
• 24-hr urinary calcium at 3 months if chronic >3 g/day.

Post-cycle / discontinuation:

• HSV outbreak count over 6 months. If unchanged from on-cycle, lysine wasn't providing benefit — re-evaluate.

For Dylan specifically: the June 2026 bloodwork panel already covers albumin and basic chemistry. Adding plasma lysine and arginine is a $30-60 incremental add-on at most labs; only worth ordering if he develops HSV symptoms or starts chronic supplementation.