TB-500 vs thymosin alpha-1

Both names start with "thymosin" because both were first found in the thymus, the small gland behind your breastbone that trains your immune cells. That's where the family resemblance ends. One works on repair and the other works on the immune system, so the useful question isn't which one is better, it's which problem you actually have.

TB-500 is a short, lab-made piece of a protein called thymosin beta-4, which nearly every cell in your body makes and uses to move and rebuild. People take it when something healed most of the way and stopped, a tendon, a calf, a shoulder that still complains on the stairs. TB-500 has no approval anywhere, and most of what's known comes from animal work and from the full-length parent protein, which isn't quite the same thing as the fragment in the vial.

Thymosin alpha-1 is a different molecule entirely, and it's the one with paperwork. It's sold as Zadaxin in a number of countries outside the US for chronic hepatitis B and C, and it's been in clinical trials since the 1980s. People buying research vials take it for immune support, the woman who catches every cold the kids bring home, or who's thinking about how the immune system slows down with age. In plain terms, TB-500 is the contractor and thymosin alpha-1 is the security team, and hiring one doesn't get you the other.

The mix-up is common enough that "is TB-500 the same as thymosin alpha-1" is a real search. It isn't, and they don't swap in for each other. If you're sorting through the repair side, our BPC-157 vs TB-500 comparison covers the pair people usually weigh against each other, and our healing and repair and immune support pages list everything else on each goal.

TB-500 dosage chart by schedule dosage guide → · Thymosin alpha-1 dosage guide →

Where these come from: the TB-500 amounts are the patterns on vendor education pages, and community protocol write-ups, none of which name a source, plus a veterinary instruction for horses. The thymosin alpha-1 amounts are from the Zadaxin product information and two small published studies that ran 8 weeks at 1.6 mg, with the 1.5 to 2 mg range from vendor pages. No label or human dosing study sets any TB-500 figure. The units to draw and how long a vial lasts are on the TB-500 dosage chart and the thymosin alpha-1 dosage chart.

The doses look close on paper, both a couple of milligrams twice a week under the skin, and that's a coincidence of scheduling, not a sign they're interchangeable. A 10 mg vial holds about four to five TB-500 doses and six thymosin alpha-1 doses, and either one goes on a 28-day clock in the fridge once water goes in.

People do search for the two together, often with BPC-157 in the same breath, and the ones who run them describe a repair peptide and an immune peptide over the same few weeks. That's a reported practice, not a tested one, since no study or label covers the pairing and no vendor we track sells them as a blend.

What people describe is keeping them as separate injections, each on its own dosage page schedule. Both are twice a week, so they can share injection days, but TB-500 usually drops to once a week after its first month or so while thymosin alpha-1 keeps going at twice a week. It's two calendars on the fridge, and they don't have to agree. If thymosin alpha-1 is already paired with something else in your plan, its dosage page covers the pairings people report.

1. Flawless Compounds10 mg · $27.50 $2.75/mg
2. Glow Aminos10 mg · $27.50 $2.75/mg
3. Evolve BioPep10 mg · $29.99 $3.00/mg
4. Next Gen Peptides20 mg · $64.00 $3.20/mg
5. Alpha Labs10 mg · $34.99 $3.50/mg

1. Glow Aminos10 mg · $35.75 $3.58/mg
2. Flawless Compounds10 mg · $35.75 $3.58/mg
3. Amino Club10 mg · $39.99 $4.00/mg
4. Evolve BioPep10 mg · $39.99 $4.00/mg
5. Solyn10.82 mg · $49.50 $4.57/mg

Compare both in the app. A 6-week TB-500 phase at the common amount uses 24 to 30 mg, and 8 weeks of thymosin alpha-1 at 1.6 mg uses 25.6 mg, so compare vendors on the real price per milligram against that total rather than the price of one vial. Look for third-party purity and identity testing on both, since a research vial of either one is only as good as the lab report behind it. Vendors on PPL carry confidence labels, from High confidence to New vendor, so you can see at a glance how much we know about each.

TB-500: the reports people share most are brief redness or irritation where they injected, and now and then mild tiredness during the twice-weekly phase. These are community reports rather than findings from a study, because no large human safety study of TB-500 exists. Most of what's known about safety comes from animal work and from the parent protein, so the long-term picture is a genuine blank.

Thymosin alpha-1: the Zadaxin product information lists injection site redness and discomfort among its common effects, and some people report feeling flu-ish after the first few doses. The label says it should be considered off-limits for people whose immune systems are deliberately suppressed, such as after an organ transplant, unless the benefit clearly outweighs the risk. That's the one interaction here that needs real care. We found no study of it in people on immunosuppressant medicines.

Neither one has a studied interaction with the other. The thymosin alpha-1 safety record comes from the approved product, which is made and tested to drug standards, and a research vial doesn't come with that promise, which is why the lab report matters.

Zadaxin has a label and a prescriber behind it outside the US. TB-500 has neither, and any vial of either one bought online is sold for research. You knew that, it's why you're reading this and not the label.