Flu-like side effect on TB-500 — is this a real thing or am I just sick?
28 posts
Second pin of my first TB cycle, 5mg Sub-Q in the flank. About 8 hours later — chills, low-grade ache, tiredness, mild headache. No fever I could measure but the subjective 'I'm coming down with something' thing was unmistakable.
Lasted maybe 18 hours, then gone. Next pin 3 days later, same reaction but milder. By pin 5 it was absent.
Searching the forum I see a handful of people mention this and then it gets shrugged off. Is this a documented thing for TB-500 specifically? Endotoxin contamination? Immune reaction to the fragment? Placebo?
10 Replies
212 posts
Real thing. Happens to a minority of users, especially on the loading doses. Most reports describe exactly what you describe — first 1-3 pins have a mild flu-feel, tolerance develops, gone by week 2. Mechanism is almost certainly a transient immune/cytokine response to the peptide itself or a trace impurity.
- CJC-1295 no DAC · 100 mcg · pre-bed · sub-Q
- Ipamorelin · 200 mcg · pre-bed · sub-Q
- BPC-157 · 500 mcg · 2x/day · sub-Q
32 posts
Got this exact pattern on my first TB cycle. Freaked me out the first time. By the 4th pin it was a 'oh, this again' shrug. Tolerized out completely.
117 posts
Could be endotoxin in the batch. High-purity TB from a reputable source typically has fewer reports. Low-end vendors seem to produce it more often. If you haven't vetted the vendor's COA for endotoxin levels, that's a place to look.
28 posts
@showmethestudy I asked the vendor, they sent HPLC but no endotoxin result. Noted as a dig-deeper item for the next vial.
97 posts
Dose-splitting can blunt it. 2.5mg x2 over a day instead of 5mg single pin on the same day. Less cytokine spike, milder effect.
- CJC-1295 no DAC · 100 mcg · pre-bed · sub-Q
- Ipamorelin · 200 mcg · pre-bed · sub-Q
- BPC-157 · 250 mcg · 2x/day · sub-Q
28 posts
Appreciated everyone. Symptoms gone by pin 5 as predicted. Continuing the cycle.
52 posts
Worth a pinned note for newbies: 'if you get mild flu-feel on first 1-3 pins of TB, it's commonly reported and usually resolves. If it escalates or doesn't go away by pin 4, stop and reassess.'
- BPC-157 · 250 mcg · 2x/day local · sub-Q
- TB-500 · 2 mg · weekly · sub-Q
10 posts
Yeah this is real. I've pinned TB multiple times across different batches and got the exact same thing first two pins, mild flu feel for like 12-18 hours. Third pin onwards nothing. Most people either don't talk about it or they're running it with other stuff so they can't isolate what caused it. The dose-split thing works too, I've done both ways. Don't overthink it, your body's just responding to the peptide intro, it'll pass.
16 posts
Yeah, it's real. I've seen it enough times that I stopped being surprised by it. Immune system just doesn't like the first exposure to the fragment, mild inflammatory response kicks in, then your body adapts. Dose splitting helps if you wanna avoid it next time, but honestly most people just push through the first few pins and call it a day. Not dangerous, just annoying.