Can You Microdose Retatrutide? · BioOptimization Collective

Can You Microdose Retatrutide?

Let’s Clear This Up.

This comes up a lot, so I want to reframe an important point.

When someone tells me they’re “microdosing” retatrutide because they’re splitting a 2 mg weekly dose into four 500 mcg injections, that is not microdosing.

That’s called split dosing, and there’s a big difference.

What Microdosing Actually Means

In pharmacology, microdosing has a specific definition:

Less than 1/100th of the dose that produces a measurable pharmacological effect.

At that level:

You don’t meaningfully activate receptors
You don’t reach therapeutic blood levels
You don’t get real metabolic or appetite effects

So when we’re talking about drugs like retatrutide, true microdosing does not work.

What Most People Are Really Doing:

Split Dosing

If your total weekly dose stays the same, but you divide it into smaller, more frequent injections, that’s split dosing.

Example:

2 mg once per week
1 mg twice per week
500 mcg four times per week

All of these add up to 2 mg per week.

The total weekly dose hasn’t changed — only how it’s delivered.

Why Split Dosing Can Make Sense

Retatrutide has a long elimination half-life of about 6 days.

That means:

After 6 days, roughly half of the injected amount is still in your system
Each new dose stacks on top of what hasn’t been eliminated yet

Over time, this creates a rolling average concentration in the bloodstream.

Eventually, you reach what’s called a steady state, where the amount you’re injecting equals the amount your body is eliminating.

This usually takes about 4–5 half-lives, regardless of how often you inject.

What matters most is total weekly dose, not injection frequency.

Why Microdosing Retatrutide Doesn’t Work

True microdosing never allows you to:

Reach steady state
Achieve sufficient receptor activation
Maintain concentrations high enough to produce results

GLP-based drugs have a threshold effect. If you don’t reach that threshold, nothing meaningful happens.

That’s why taking tiny fractions of the dose and hoping for benefits simply doesn’t work.

When Split Dosing Is Useful

Split dosing does not change how much drug is in your system at steady state.

What it does change:

Peak concentrations
Trough concentrations

By smoothing those peaks and troughs, split dosing can:

Reduce nausea
Reduce fatigue
Improve GI tolerability

This is the same reason testosterone is often split into multiple injections — not to increase effectiveness, but to improve stability and side-effect management.

Bottom Line