Selank vs. Semax: Which One Does What?

If you have been looking into peptides that affect the brain, you have likely tripped over two names that sound like characters from a sci-fi novel: Selank and Semax.

While they are both heptapeptides (which is just a fancy way of saying they are made of a chain of seven amino acids), they have very different jobs. One is more about your internal peace, and the other is about brain protection and recovery.

What is Semax?

Semax is a synthetic version of a fragment of ACTH. That is a long acronym for a hormone, but Semax specifically avoids the parts that affect your adrenal glands, so it does not cause hormonal side effects.

Instead, it works by bumping up brain-derived neurotrophic factor, or BDNF. Think of BDNF as a fertilizer for your brain cells.

What we know about Semax:

• Stroke Recovery: It has been used in Russia since the 1990s as a standard treatment for ischemic stroke (a stroke caused by a blood clot).
• Brain Support: It protects nerves and works with the brain's dopamine and serotonin systems, which are chemicals that manage mood and motivation.
• Imaging Evidence: Scientists have used fMRIs (brain scans that show blood flow) to validate that it actually does something in the brain.

What is Selank?

Selank is a synthetic version of something called tuftsin. Its main claim to fame is that it interacts with your GABA-A receptor system.

If that sounds familiar, it is because that is the same system targeted by benzodiazepines (common anti-anxiety meds). However, Selank manages to do this without the typical downsides like feeling sleepy or becoming dependent on the drug.

What we know about Selank:

• Calm without the Fog: It offers effects similar to anti-anxiety meds but without the sedation or risk of addiction.
• Immune Support: It actually has some antiviral properties and can help with things like the flu by inducing interferon (a protein your body uses to fight germs).
• Chemical Balance: Like its cousin, it also helps normalize serotonin and dopamine while boosting that brain-fertilizer protein, BDNF.

What is the catch?

Scientists are still working on these—turns out the human body is complicated. Who knew?

Both of these have a Grade B or B- evidence rating. While they have been used in Russia for over 25 years, they have not been put through large Western clinical trials.

The current evidence gaps include:

• Lack of Western Approval: Neither is FDA-approved, though they are approved for use in Russia.
• Delivery Questions: Selank is often used as a nasal spray, which leaves scientists wondering exactly how much of it actually gets into your system.
• Limited Replication: Most of the data comes from Russian clinical practice, with very little independent testing in the West.

Which is which?

If you are comparing them, Semax is primarily recognized for neuroprotection and stroke recovery. Selank is more focused on GABA modulation and immune support.

This is a great one to bring up with your doctor. You can find peptide-experienced physicians in our Find a Doctor directory.

This content is sourced exclusively from TruthTides clinical reference data and does not constitute medical advice.