At 20-25 mg in a young man with normal endogenous levels: usually subtle to nothing. Some users report mild libido bump (especially in the first 1-2 weeks before HPG axis adapts), slight increase in skin oiliness and acne (peripheral 5α-reductase conversion in skin), and occasional mild irritability or emotional reactivity (pro-androgenic). The "felt effect" is small and frequently indistinguishable from placebo in blinded settings.

At 50-100 mg in a young man: more reliable androgenic side-effect profile — measurable acne, scalp hair shedding in predisposed (AR CAG-short, family history of androgenetic alopecia), mild aggression/irritability — but also more peripheral aromatization, so paradoxically users sometimes report estrogenic symptoms (water retention, occasional nipple sensitivity, mild fatigue) layered on top. The mix-signal effect is characteristic: DHEA at this dose pushes both axes simultaneously and the body doesn't know which signal to follow.

Onset: gradual — days to weeks. No acute "felt" dose comparable to caffeine, modafinil, or even pregnenolone. Subjective effects (when present) build over the first 2-4 weeks and plateau.

Discontinuation: uneventful in most users. Transient HPG suppression is documented but mild — endogenous testosterone may dip 10-20% for 2-4 weeks before normalizing. No withdrawal syndrome.

Mood-libido polarization. Anecdotal reports cluster bimodally: a subset of users (typically lean men with high aromatase or high body fat) report frank malaise, fatigue, and depressed libido on DHEA — consistent with net-estrogenic conversion. The opposite subset (typically men with shorter AR CAG repeats and lower body fat) report mild stimulation, libido bump, and energetic mood — consistent with net-androgenic conversion. This bimodal response is part of why population-average trials in young adults consistently fail: the average masks two opposing responder phenotypes.

• Tolerance to direct effects: minimal. DHEA doesn't downregulate its own receptors meaningfully. The receptors it affects (AR, ER, GABA-A, NMDA) don't desensitize on the timescale of DHEA's pharmacokinetics.
• HPG-axis adaptation: real and dose-dependent. Sustained exogenous DHEA → mild downregulation of LH/FSH → modest reduction in endogenous testicular T production. Magnitude scales with dose; at 25-50 mg/day in older adults, suppression is clinically negligible; at 75-100+ mg/day in young men with intact HPG, suppression can be measurable.
• Recommended cycle structure:
  • Adrenal insufficiency / Intrarosa: continuous, no cycling needed (replacement model).
  • Older-adult replacement (women >50 with documented low DHEA-S): continuous with quarterly bloodwork; some clinicians cycle 12 weeks on / 4 off to assess endogenous response.
  • Younger users (off-label, biohacker context): 8-12 weeks on / 4-8 weeks off to allow HPG recovery. Mostly theatrical at age 20 — endogenous production is already saturated, cycling exogenous on top doesn't meaningfully change anything.
• Reset protocol: simple discontinuation. Endogenous DHEA-S returns to baseline within 2-4 weeks (long half-life of sulfated reservoir means a "rebound" doesn't really happen). HPG axis typically recovers within 4-8 weeks; if measurable suppression persists beyond 12 weeks, recheck LH/FSH/T and consider SERM-mediated restart (clomiphene/enclomiphene short course).
• Stacking-tolerance note. Tolerance to exogenous-androgen stacks (testosterone, anabolic steroids) is layered separately and is not improved or accelerated by DHEA. DHEA on top of TRT is not a "tolerance-extender" — it just adds estrogenic load.

Synergistic with

• None relevant at Dylan's age. The post-50 deficiency-replacement context pairs DHEA with pregnenolone (parallel adrenal-axis replacement), low-dose TRT (when documented hypogonadism), or vitamin D + calcium for bone density. Those pairings exist because both partners address a documented age-related deficiency; the logic does not transfer to a 20yo at peak production.
• In DOR / IVF adjunct context, DHEA is often stacked with CoQ10 (mitochondrial support — the AMPK-SIRT1 mechanism from PMID 38453773), DHA, and vitamin D. Narrow clinical indication only.

Avoid stacking with

• [enclomiphene] — both modulate the HPG axis from different angles; combining without bloodwork-driven rationale risks E2 elevation (DHEA → aromatization) layered onto enclomiphene's SERM-driven endogenous T rise. Discord anecdotes in this file show users empirically running this combo for "smoother" enclomiphene experience — pharmacologically incoherent in a 20yo with intact HPG. Coordinate via labs, don't combine blind.
• [testosterone-enanthate] — exogenous T already saturates androgen receptors and shuts down endogenous production; DHEA on top adds peripheral estrogenic load via aromatization with no incremental androgenic benefit. Counterproductive on TRT — most clinicians actively remove DHEA when starting TRT.
• Aromatase-driving conditions (high body fat, zinc deficiency, alcohol use) — amplify the DHEA → E2 conversion fraction, pushing the risk profile estrogenic.
• MAO inhibitors and bipolar-treatment regimens — mood destabilization signal.

Neutral / safe co-administration

• Canonical stack (omega-3, magnesium, vitamin D, creatine, citicoline, NAC, etc.) — no meaningful interactions.

• CYP3A4 substrate (modest). Strong CYP3A4 inhibitors (ketoconazole, itraconazole, ritonavir, clarithromycin, high-volume grapefruit juice) can elevate DHEA exposure 1.5-2×; strong inducers (rifampin, carbamazepine, phenytoin, St. John's Wort) can drop it ~30-50%.
• Aromatase inhibitors (anastrozole 1 mg/day, letrozole 2.5 mg/day, exemestane) — block DHEA → E2 conversion, shifting balance toward androgens. Used clinically only in oncology and rarely in supervised hormone optimization; not a pairing for a 20yo.
• SERMs (clomiphene, enclomiphene, tamoxifen) — overlapping HPG modulation; coordinate via labs.
• SSRIs / SNRIs / lithium / mood stabilizers — case reports of mania induction with DHEA in bipolar-spectrum users; relative caution.
• Anticoagulants (warfarin) — modest case-report interactions via CYP-mediated effects; INR monitoring if combined.
• Oral contraceptives — DHEA modestly raises free androgens that OCP-induced high SHBG would otherwise suppress; clinically minor.
• Insulin / oral hypoglycemics — DHEA modestly improves insulin sensitivity in older adults; potential for additive hypoglycemia in tight glycemic control (rare relevance).
• Glucocorticoids (prednisone, dexamethasone) — suppress endogenous DHEA-S. The Petri 2002 SLE rationale was that prasterone could allow corticosteroid dose-sparing in chronic users.

• CYP3A4 / CYP3A5 polymorphisms (CYP3A5*3 nonexpressor allele common in non-African populations) — modest effect on DHEA clearance; usually clinically minor.
• CYP19A1 (aromatase) variants — rs10046, rs700518, and intron-4 TTTA-repeat polymorphisms determine aromatase activity. High-activity variants push more DHEA → E2 conversion, shifting risk profile estrogenic and reducing androgenic yield. Relevant to the bimodal-responder pattern described in Subjective Experience.
• AR CAG repeat length (exon 1 of androgen receptor) — shorter repeats (<22) = more sensitive AR signaling per unit androgen, magnifying both desired effects (libido, mood) and adverse effects (acne, hair shedding). Longer repeats (>24) = blunted androgen response.
• SRD5A2 (5α-reductase type 2) variants — drive scalp hair-shedding and prostate-related side-effect risk via DHT production.
• 3β-HSD2 and 17β-HSD variants — affect upstream conversion rate; minor clinical relevance.
• HSD3B1 (1245A>C) — adrenal-permissive variant linked to prostate cancer prognosis; relevant if family history of prostate cancer.
• 23andMe will surface CYP19A1, AR CAG region (indirectly), and HSD3B1 in Dylan's June 2026 results. Even with the data, the answer at 20 is "moot — endogenous DHEA-S is at lifetime peak, no supplementation indicated regardless of genotype." Genotype would only become relevant if a real deficiency emerged decades from now.

US OTC status is an FDA exemption rooted in 1994 DSHEA — DHEA is grandfathered as a dietary ingredient even though it's pharmacologically a steroid hormone. Most other developed countries treat it as Rx. Not relevant for Dylan — listed for completeness.

Not applicable for Dylan — not on protocol. If hypothetically considered after future bloodwork:

• Baseline panel (pre-start): DHEA-S (reference: 280-640 µg/dL in 20-29yo men; 65-380 µg/dL in 20-29yo women), total testosterone, free testosterone (calculated or measured), estradiol (sensitive LC-MS/MS assay, not standard ECLIA), SHBG, LH, FSH, fasting lipids (TC, LDL, HDL, TG), fasting insulin + HbA1c, LFTs (ALT, AST, GGT, bilirubin), PSA (if male >40 or family history of prostate cancer), CBC (hematocrit).
• During use: Same panel at 8-12 weeks; primary read is whether DHEA-S has moved into the intended range without exceeding age-adjusted upper bound and whether T:E2 ratio has remained physiological.
• Post-cycle (if cycled): Same panel 4-6 weeks after cessation to confirm HPG axis recovery (LH/FSH back to baseline, endogenous T restored).
• Subjective tracking alongside labs: acne/skin score, libido VAS, mood VAS, sleep quality, scalp hair shedding (photo log every 4 weeks). Bimodal-responder pattern means the labs alone undersell what's happening — the subjective tells are diagnostic of whether the user is net-androgenic or net-estrogenic on their dose.
• For postmenopausal Intrarosa users: vaginal pH, maturation index, dyspareunia VAS — local response, not systemic labs (since systemic absorption is minimal).
• For DOR / IVF adjunct: AMH, AFC (antral follicle count), FSH; oocyte yield and pregnancy outcome as primary read.