All compounds
Over the counter Published: RCT evidence Extensive real-world use

Vitamin D3: dosing, timing and what to expect

A fat-soluble hormone precursor, not really a vitamin. Deficiency is common indoors and at latitude, and it associates with lower testosterone — though supplementing to correct a deficiency helps far more reliably than supplementing on top of a normal level.

Also known as cholecalciferol, D3

Educational research reference Supplements
Quick reference. Everything you need to run Vitamin D3 — dosing, frequency, reconstitution math for the vial sizes people actually buy, and what it stacks with. For anything specific to your situation, ask the Guru.

Vitamin D3 quick start

Route
Oral
Typical dose
2,000–5,000 IU daily
Frequency
Daily
Half-life
Stores in fat for weeks — a missed day is genuinely irrelevant.
Cycle
Continuous, ideally guided by bloodwork twice a year.
These are the numbers people actually run, drawn from the published record and from what the community has settled on over time. Educational reference, not medical advice — a starting point to work from, and one you can adjust as you learn how you respond.

How to run it

How often
Daily
Cycle length
Continuous, ideally guided by bloodwork twice a year.
Half-life
Stores in fat for weeks — a missed day is genuinely irrelevant.
Route
Oral
Consistency matters more than perfect timing. Pick a slot in your day you will actually keep, and let DoseIQ handle the rest.

What people actually run

The one supplement almost every TRT clinic checks, because low D and low free testosterone travel together often enough to be worth ruling out.

This is accumulated community practice — years of real-world use across a large number of people, converging on numbers that work. It is not a controlled trial, and for most compounds here no such trial exists or is ever likely to. That makes this the most reliable dosing signal available, and it is a good deal better than guessing.

What to expect

Most people tolerate Vitamin D3 well. Here is what is worth knowing going in, so nothing catches you by surprise.

Fat-soluble, so it accumulates — this is one of the few supplements where more is actively worse. Sustained high intake drives calcium into soft tissue rather than bone. Take it with K2 and get a 25-OH-D level rather than guessing; "I feel like I need more" is not a measurement. Interferes with nothing in a TRT protocol, but correcting a real deficiency can shift how you feel enough to be mistaken for a dose change.

Preparing it

Vitamin D3 does not need reconstituting — it comes ready to use.
Track this in DoseIQ Browse all compounds

This page is an educational research reference and is not medical advice. Dose figures reflect the published record and what the community has converged on — starting points to weigh, not instructions. Consult a qualified healthcare provider before starting any protocol.