How much does hCG build up with twice weekly dosing?

At steady state on a twice weekly schedule, the model's level is about 1.16 times what one dose gives, and it swings about 3.59:1 between the peak and the trough before the next dose. Longer gaps between doses mean less build-up and a bigger swing.

Is this chart my actual hCG level?

No. It is a modeled estimate from a published half-life, using the same one-compartment model as the Dose Track app. Real levels vary with body weight, injection site, kidney and liver function and other factors, and only a lab test measures them. It is not medical advice.

hCG Half-Life: Peak and Steady State Chart

Q: When does hCG peak after a dose?

Blood levels peak about 20 hours after an injection under the skin, according to Ovidrel (choriogonadotropin alfa) label. Individual timing varies with the injection site, the amount and the person.

Q: How long does hCG take to reach steady state?

About 6 days of regular dosing at the same amount and interval, which is 5 half-lives. With a half-life of about 29 hours, levels reach about 50% of steady state after 29 hours and about 90% after 4 days. Changing the dose or interval starts a new climb toward a new steady state.

Q: How long does hCG stay in your system after the last dose?

Roughly 5 half-lives, about 6 days, until about 97% has cleared in the model. Half is gone about 29 hours after levels start falling. Real clearance varies from person to person, and a drug can still have effects after levels are low.

Short answer: hCG has a half-life of about 29 hours (Ovidrel (choriogonadotropin alfa) label) and reaches steady state after about 6 days of regular dosing. Levels peak about 20 hours after an injection under the skin. On a twice weekly schedule the model builds up to about 1.2× a single dose, with a peak-to-trough swing of about 3.59:1.

What do hCG levels look like with twice weekly dosing?

Relative units: 1 on the scale is one full dose. There is no FDA label dose for this use, so the chart shows the shape of the curve, not an amount. Dashed line: 5 half-lives. Change the amount or schedule in the calculator.

When does hCG peak after a dose?

Levels peak about 20 hours after an injection under the skin.

How long does hCG take to reach steady state?

With regular dosing at a fixed amount and interval, levels climb toward steady state by the same fraction every half-life, whatever the dose. At a half-life of about 29 hours:

Time from the first dose to each share of steady state, hCG (half-life 29 hours).
Share of steady state	Half-lives	Time
50%	1	29 hours
75%	2	2.4 days
90%	3.3	4 days
97% (Dose Track's steady-state rule)	5	6 days

How much do hCG levels swing between doses?

The longer the gap between doses compared with the half-life, the bigger the swing from peak to trough and the less the levels build up. These ratios do not depend on the amount.

Steady-state peak:trough and build-up by dosing interval, hCG, in Dose Track's model.
Interval	Peak : trough	Build-up vs one dose
Daily	1.16 : 1	2.29×
Every other day	1.69 : 1	1.47×
Twice weekly	3.59 : 1	1.16×
Weekly	25.5 : 1	1.02×
Every 2 weeks	over 1,000 : 1	1×

Build-up is the accumulation ratio 1 / (1 − e^−k·τ), with k = ln 2 / half-life and τ the interval.

How long does hCG stay in your system?

After the last dose, about half is gone every 29 hours. After 5 half-lives, about 6 days, roughly 97% has cleared in the model.

Where do these numbers come from?

The FDA Ovidrel label reports a terminal half-life of about 29 hours after an injection under the skin, with levels peaking about 12 to 24 hours after the shot. Ovidrel is recombinant hCG studied mostly in women; Novarel and Pregnyl are labeled for injection into muscle, so the Ovidrel figures are the closest label data for an injection under the skin.

The curve uses the half-life, time to peak, route and bioavailability built into the Dose Track app for hCG, and the same one-compartment model with first-order absorption. These are modeled estimates from published half-lives, drawn with the same one-compartment model as the Dose Track app. Real levels vary from person to person, and only a lab test measures them. This is not medical advice and not a dosing recommendation; dosing decisions belong with you and your prescriber.

Vial sizes and syringe math are in the hCG (Human Chorionic Gonadotropin) guide.

When does hCG peak and reach steady state?