TB-500 common uses, half-life, side effects and more

TB-500 is a synthetic peptide sold as a research chemical for injury recovery. The name most precisely refers to a short fragment of thymosin beta-4 called Ac-LKKTETQ. Sellers and community guides often treat TB-500 and full-length thymosin beta-4 as the same molecule. They are not the same thing. A vial labeled TB-500 may hold either one. People mainly inject it in gray-market protocols to recover from tendon, ligament, muscle, and other soft-tissue injuries. It is not an approved medicine in any country. It is also banned in sport at all times.

• Recovery from tendon, ligament, muscle, and joint injuries
• Healing after surgery or an acute soft-tissue injury
• Ongoing or chronic injuries that have been slow to settle
• General recovery support between hard training sessions
• Pairing with BPC-157 in a soft-tissue healing stack

Daily, every other day, or twice weekly

Reported subcutaneous doses run from about 1 mg daily up to 2 to 2.5 mg twice weekly. No single protocol is agreed. One school injects about 1 mg every day or every other day and points to the fragment's short time in the blood as the reason to dose often. The other uses 2 to 2.5 mg twice weekly for a 4 to 6 week loading block before stepping down to weekly or every other week. Experienced forum users often settle near 2 to 5 mg per week in total. Some people inject the same amount into muscle near an injury instead of the abdomen. Amounts near 5 mg twice weekly appear for severe injuries. The loading-then-maintenance schedule traces more to dosing-guide websites than to first-hand reports.

• Most people inject into the abdomen or thigh rather than the injury site because the peptide is thought to act throughout the body
• The BPC-157 stack is injected as two separate shots rather than one mix because the two peptides run on different schedules
• Users typically run it for a block of weeks and then stop or cut back rather than dosing without a break

Full-length thymosin beta-4 has a plasma half-life of roughly 0.5 to 2 hours after an intravenous dose. No one has measured a half-life for the injected TB-500 fragment itself or for the subcutaneous route people actually use. Weekly dosing is a community habit rather than a measured schedule.

• Injection-site redness, itching, or swelling of the kind expected from any subcutaneous peptide shot
• Tiredness, mental fog, and lethargy reported by users in the first days of use
• Headache, lightheadedness, or a brief flu-like feeling reported soon after a dose

TB-500 is the acetylated LKKTETQ fragment of thymosin beta-4. That fragment is the part of the protein that binds actin. The whole protein sequesters actin monomers and helps cells remodel their skeleton, migrate, and grow new blood vessels. The fragment keeps the actin-binding site. Laboratory work shows it driving endothelial migration and new vessel growth about as strongly as the full protein. Other important parts of thymosin beta-4 biology sit in regions the fragment lacks. The anti-inflammatory and cell-survival actions come from those missing segments and should not be assumed for TB-500. A 2024 study found the intact fragment did not speed wound healing in a cell assay. Only a metabolite of it did. How much of any of this reaches human tissue after an injection is unknown.

Almost all of the evidence is for full-length thymosin beta-4 rather than the TB-500 fragment. Animal and cell studies of the full protein support roles in wound repair, blood vessel growth, and tissue healing. Human data on the full protein are limited to early intravenous safety studies in healthy volunteers and topical eye-drop trials. The largest eye-drop program missed its main goal in late-stage testing. No published human study has given the TB-500 fragment itself to people for healing. A 2024 laboratory study found the intact fragment did not speed wound healing in a cell test. The injected protocol people follow rests on forum practice and on extrapolation from the full protein. Its dose, timing, and benefit have never been tested in a controlled human trial.

• Not approved as a medicine in any country and sold only as a research chemical with unverified identity, purity, dose accuracy, and sterility
• Named directly under WADA section S2 and banned in sport at all times
• People with a current or past cancer should avoid it because thymosin beta-4 can promote the cell migration and new blood vessels that tumors use to grow and spread
• A vial sold as TB-500 may contain either the short fragment or the full-length protein because sellers use the name for both
• Injecting the fragment may provoke an immune reaction that no human study has ever measured
• Avoid it in pregnancy and while breastfeeding because there is no human safety data