DOSEGUY

ISRIB

guinea pig

Also seen as: trans-ISRIB, integrated stress response inhibitor

The Dose Guy’s verdict
Sep 1, 2026
5 sources

ISRIB has the strongest preclinical cognition data I’ve seen: mice with traumatic brain injuries and age-related decline got their memory back, and the mechanism points to a specific molecular target. The problem is that no one has given it to a person in a trial. No phase 1, no safety study, nothing. If you want a nootropic you can run today, semax and noopept have human dosing behind them. I’m watching ISRIB closely. I’m not running it.

Would I take it?Not yet. Best mouse story on the shelf, zero human data.

What it is

ISRIB is a small molecule that resets the cell’s main stress brake, a pathway called the integrated stress response. When neurons take damage from aging, injury, or toxic proteins, they flip this brake and dial down protein production as a defense. The brake is useful in a crisis, but it sticks, and a neuron stuck in stress mode stops building the proteins it needs for memory and plasticity. ISRIB forces a protein complex called eIF2B back into its active shape, overriding the stuck brake and letting the neuron work again.

On the nootropic shelf this sits near dihexa as a preclinical compound with a dramatic reputation, except ISRIB’s underlying science is intact where dihexa’s is cracked. The effect in mice is large and tied to a specific molecular target, though one Alzheimer’s-model study found no rescue where others did. The gap is that nobody has confirmed any of it translates to people.

What the research shows

No human trials. Zero. Everything below is animal or in-vitro work. Read it as “interesting,” not “evidence it works in you.”

Every result is a mouse or a cell dish. The preclinical story is unusually strong for a compound this far from the clinic:

A cell screen identified ISRIB at 5 nM potency for reversing eIF2alpha phosphorylation effects. Treated mice showed enhanced spatial and fear-associated learning.eLife 2013 · cell screen · mice
ISRIB reversed spatial memory deficits and improved working memory in old mice, restoring hippocampal spine density and neuronal signaling properties.eLife 2020 · aged mice
In two traumatic brain injury models, ISRIB reversed hippocampal-dependent cognitive deficits even when given weeks after injury. The improvement persisted after treatment ended.PNAS 2017 · TBI mice
During proteotoxic stress, ISRIB impaired ubiquitin-proteasome degradation and caused accumulation of polyubiquitylated, insoluble defective ribosome products.Commun Biol 2024 · cell study
A 2022 ISRIB neural stem cell paper was retracted. The core mechanism studies and the memory results in aged and injured mice are unaffected.Hindawi 2023 · retraction notice
No clinical trial has evaluated ISRIB in any condition.as of Aug 2026

Realistic protocols

I’m not building a protocol from mouse injection studies and no human pharmacokinetics. The forum protocol runs 2.5 to 10 mg swallowed or sublingual, sometimes cycled a few days on and off, chosen by rough scaling from mouse doses. That is a guess built on guesses. If you run it anyway, start at the low end, keep runs short, and understand that you have no human safety ceiling to reference. The proteasome concern on this page is worth reading before you decide.

Side effects

No human has been studied on ISRIB, so the side-effect profile is a blank page with one worrying footnote:

unknownOverriding the stress response may also impair proteasome-mediated protein cleanup, causing damaged proteins to accumulate. That tradeoff has no human data behind it.
anecdotalForum users report headache and mild fatigue, usually at higher doses and early in a run.
unknownNo long-term exposure data in any species at doses people actually take. The mouse studies ran briefly.

Where to buy

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