Frequently asked questions

We use a transparent 3-tier model (advanced, linear-regression, simple) plus an inherited tier, all documented on our methodology page. The most common reason a curve looks different here is that we apply a dose-scaling exponent for compounds whose peak concentration is known to be non-linear in dose — notably testosterone esters.

We cannot assess whether any protocol is safe for any individual. Anabolic-androgenic steroids carry documented risks including cardiovascular disease, liver damage (with orals), endocrine disruption, psychiatric effects, and dependence. This site provides pharmacokinetic modeling and harm-reduction information, not safety assessments. Anyone considering use should consult a qualified healthcare provider and understand the legal status of these compounds in their jurisdiction.

The detection-time estimator combines a half-life-based model with published detection windows from anti-doping literature. The model is an approximation. The published windows come from controlled microdose-excretion studies, which may not reflect real-world doses, durations, or individual metabolism. Detection times can be significantly longer with higher doses, longer cycles, and certain metabolites. Never use this tool to time use around a drug test.

Because you’re dosing repeatedly. Half-life describes the decay of a single dose in isolation. With ongoing dosing, each new dose is added on top of residual drug, so the combined curve (a superposition) doesn’t drop to 50% after one half-life — the newest dose is still near its peak. This accumulation is what drives the approach to steady state.

Standard practice is to draw trough bloodwork (just before your next injection) at steady state. For testosterone, this means total T, free T, estradiol (sensitive assay), hematocrit, lipids, and liver enzymes. Draw at baseline (pre-cycle), mid-cycle, and post-PCT. The peak-trough estimator can identify the trough window for your schedule. Always have bloodwork interpreted by a clinician.

Use our contact form with the compound name and, ideally, a peer-reviewed pharmacokinetic source. We prioritize adding compounds with reliable half-life and bioavailability data. Compounds without published PK data use our “inherited” or “simple” model tiers and are clearly labeled as approximate.

No. Our curves are simplified one-compartment approximations meant to illustrate patterns — accumulation, timing, peak-to-trough swings, and clearance. Real blood levels depend on genetics, body composition, injection technique, and organ function. Treat the curve as educational. Confirm any real-world decision with bloodwork.

When “Reference ranges” is toggled on in the chart header, a shaded green band shows the eugonadal total testosterone range (roughly 300–1000 ng/dL). The band is a population reference, not a personal target. Optimal levels within the band depend on symptoms, not just the number — and must be guided by bloodwork and a clinician.

Low estradiol (E2) causes joint pain, loss of libido, dry skin, mood disturbance, and lipid deterioration. It can happen when aromatase inhibitor dosing overshoots. The fix is to reduce or stop the AI and let E2 recover (which takes several days to a week depending on the AI). Always dose AIs based on estradiol bloodwork, not on a fixed schedule. Read our aromatase inhibitor timing guide for details.

PCT timing depends on the ester half-life. Short esters (propionate) clear in days, so PCT starts about 4-5 days after the last injection. Long esters (enanthate, cypionate) take 2-3 weeks. Very long esters (decanoate, undecanoate) take 4-6 weeks. The PCT planner estimates clearance timing from the compound half-life. Starting too early fights still-elevated androgen levels; starting too late prolongs suppression.

When two or more compounds with a documented interaction are added to the plotter, a dismissible yellow banner appears below the chart explaining the concern. Our warnings surface known pairings from the literature — they are advisory and non-blocking. The absence of a warning does not mean a stack is safe; it means we have no flagged data for that pairing.

The PCT Planner takes the compounds you used and your last-dose date, estimates when each clears (using ≈5 × the half-life), identifies the latest clearance as the earliest sensible PCT start, and suggests a representative SERM (Nolvadex + Clomid) schedule from there. It is a harm-reduction estimation tool — actual PCT must be confirmed with bloodwork and clinical guidance.

Yes. SARMs suppress the HPG axis through negative feedback, though typically less than equivalent doses of AAS. The degree of suppression depends on the compound, dose, and duration. RAD-140 (testolone) and S-23 are among the most suppressive. Ostarine is less suppressive at low doses but still measurably lowers LH, FSH, and total testosterone. Bloodwork before and after a SARM cycle is essential harm reduction.

Yes. Add the same compound multiple times using “Add compound,” then set different doses or schedules per row. For example, overlay 120 mg once weekly against 60 mg twice weekly to compare peak-to-trough ratios. Each row renders as a separate colored line.

More frequent dosing at the same total weekly amount produces a smaller peak-to-trough ratio, meaning more stable blood levels. For testosterone enanthate (7-day half-life), twice-weekly injection halves the peak-to-trough swing compared to once-weekly. This reduces side effects at peak (acne, estrogen conversion) and symptoms at trough (fatigue, low mood). Read our injection frequency guide for the full explanation.