Trying P21 for a cognitive boost – what have you noticed?

Posted by caleb_climbs in General Discussion - 19 points, 4 comments.

I started a low‑dose P21 trial a few weeks ago after reading the brief on its neurogenesis claims. I’m dosing about 75 mcg/kg subcutaneously each morning, roughly 5 mg for my weight, and I’m keeping the injections in the same spot on my abdomen to avoid irritation. To be fair, I wasn’t expecting miracles, just a subtle edge in focus and memory.

After about ten days I’ve noticed that my morning “brain fog” seems a bit shorter. When I’m reading research papers I can keep my attention for longer stretches, and I’ve had a few moments where I recall details from a conversation a day or two later that I would normally forget. I haven’t felt any change in appetite, which is good because I was worried about the CNTF side effects some people mention. I did get a mild headache on the third day, but it cleared up in an hour and hasn’t returned.

I’m still tracking my sleep, mood, and any nasal irritation (none so far). Has anyone else tried P21 at a similar dose? Any tips on rotating injection sites or spotting side effects would be appreciated 👀. 🧪

Comments

• omar_m: I’ve run a similar P21 schedule for about six weeks, 70 µg/kg sub‑Q each morning, rotating between abdomen, thigh and upper arm every other day to keep the tissue from getting too fibrotic. For me the biggest noticeable thing was a slight sharpening of short‑term recall after the first week, but the effect plateaued and I started feeling occasional neck stiffness that I think was mild irritation from re‑using the exact same spot. I found switching sites and using a 30‑gauge needle helped. Keep
• caleb_climbs: Thanks for the detail, Omar. I’ll definitely start rotating sites – I was stubborn about staying in the abdomen and now see why. I’ll also grab a 30‑gauge needle; the neck stiffness you mentioned sounds like the exact irritation I was trying to avoid. I haven’t had any lingering headaches beyond day 3, but I’ll keep an eye on it in case it shows up later.
• amber464: Sounds like you nailed the site‑rotation trick, my own neck tightness cleared up after I switched to a 30‑gauge and varied spots. I’ve also seen a mild “brain‑fog‑after‑dose” dip for a day, but it usually fades. Have you logged any changes in HRV or sleep quality?
• caleb_climbs: Thanks for the 30‑gauge tip, I've only used 25‑gauge so far, so I’ll switch today. I haven’t logged HRV yet, but I’ll start with the smartwatch this week. How do you track sleep quality? You mentioned a post‑dose fog; did that happen immediately after the shot or a few hours later? 👀

Community discussion - research and educational context only. Not medical advice.