Tuftsin is a immune tetrapeptide. Splenopentin is a immune pentapeptide.
| Comparison | Tuftsin TKPR · Thr-Lys-Pro-Arg | Splenopentin SP-5 · splenopentin acetate |
|---|---|---|
| How it works | How it works Tuftsin is one of the older compounds in this library and the connection to Selank is the most useful thing about it. | How it works Splenopentin belongs to the same era and idea as thymopentin, and shares its problem. |
| What it is | A four-amino-acid immune peptide from the 1970s, and the parent of Selank. | A five-amino-acid spleen peptide, sold on an evidence base almost nobody has read. |
| Status | Research only | Research only |
| Typical dose | — | — |
| How often | Not established | Not established |
| Stays active | Nothing published | Nothing published |
| Dose comes from | No established range | No established range |
| Cycled? | Not established No established range | Not established No established range |
| What it does | ||
| Drug class | Immune tetrapeptide | Immune pentapeptide |
| Used for | An immune peptide researched for stimulating phagocytes, and the molecule Selank was designed from. | An immune peptide sold for immune support and bone marrow recovery. |
| Receptors hit | — | — |
| Numbers | ||
| Full dose line | Research only | Research only |
| Why that cycle | No schedule has been studied for this compound in people. | No schedule has been studied for this compound in people. |
| Weight / effect | Not measured in a trial | Not measured in a trial |
| Chain length | 4 residues | 5 residues |
| Common vial | — | — |
| Before you start | ||
| Route | Under the skin (subcutaneous) | Under the skin (subcutaneous) |
| Do not use if | Pregnancy or breastfeeding An autoimmune condition, where stimulating immune cells is a poor idea without advice Immunosuppressant medication, including after a transplant Anyone who wants established safety data, because none exists for this compound in humans | Pregnancy or breastfeeding An autoimmune condition, without medical advice Cancer treatment, where an unstudied peptide is not a substitute for supportive care that has been tested Anyone who wants established safety data, because none exists for this compound in humans |
What separates them
Proof behind the dose. Every dose here comes from community practice. Not one is backed by a published human study, which is worth knowing before you read the numbers as if they were equivalent.
What doesn't differ: They are both taken the same way (under the skin), aimed at the same thing (immune support) and on the same schedule (not established). Neither has a measured effect size from a published trial, so there is no number to rank them on.
What people actually report
Tuftsin
- No modern controlled human trial supports the uses it is sold for.
- It stimulates immune cells, which is not desirable in every condition.
- Signs of an allergic reaction, including spreading hives, facial or throat swelling, or trouble breathing
- Redness, heat, or pus at the injection site, which can signal infection
Splenopentin
- The research behind it is old, small and largely unrepeated.
- It affects immune cells, which is not desirable in every condition.
- Signs of an allergic reaction, including spreading hives, facial or throat swelling, or trouble breathing
- Redness, heat, or pus at the injection site, which can signal infection
Side effects are what users and trials report most often, not a complete list. Anything sudden, spreading, or breathing-related is an emergency regardless of which compound caused it.
People also compare
This comparison does not cover cost, long-term safety, or how you personally will respond. Effect figures come from separate trials in different populations and are not always directly comparable to each other. Nothing here is medical advice or a recommendation to use any of these. Talk to a clinician about your own situation.

