As per my previous posts, I've had a hell of a time tolerating any B complex. I've tried (over the years, in order): -Several multivitamins -NOW B-50 -Some CVS brand B complex -Jarrow B Right (not the folic acid "B Wrong" either) -Thorne B Complex #12 -Douglas Labs B Complex -Biotics Research B-100 -Nature Made B Complex Every single one has consistently made me feel weary, fatigued, clumsy, irritable, and just generally lousy. My eyes water a lot, and I keep wincing. I finally did what I should've done earlier this year when I set upon sorting this all out, and I broke down the B complex into individual components. I'm here to share my story, results, and hopefully leave a bit of info to help someone else who runs into this at some point. Here's from my daily log: B1 – 50mg –frustrated, feeling extremely worked, weary, wincing, long lasting B2– 100mg – no noticeable reaction, yellow urine B3 (niacinamide) - 100mg x2 – some sedation & relaxation, turned into stress/tension/social awkwardness/irritability B5 – 100mg – no noticeable reaction, maybe a bit more energy B6 - 50mg x2 – burst in energy, then tiredness until next dose. No irritability Biotin – 5000mcg x2 - feeling worked in very short time, similar to B1 but not as long lasting/severe, wincing B3 retest – 100mg x3 at once – some sedation and frustration/irritability P5P – 50mg – Very little noticeable effect with first dose, huge crash after 6+ hours, lousy mood following Keep in mind, the last 2 B complexes I tried (Biotics and Nature Made) are extremely low in RDA of each component. The Biotics one allowed me to start with 33% RDA of each component, and the Nature Made allowed me to work with the bare minimum number of components, without any activated forms. So these higher doses above were done deliberately so that I could really figure out where the side effects were coming from. All this said, I think I may have to steer away from the B complex for now. I've had exceptionally great results on Freddd's protocol, with just mB12, adB12, mFolate, and a few other cofactors. Lots more energy, much better mood, and a friend even commented that my skin looks the best ever lately. Plus I've been expanding my diet again, and including sulfur foods with much less issue. I'm going to get a panel done for my levels of the B's, specifically B6/B2 due to their relation to methylation. But in the meantime, are there other changes I could try based on my tests? I've heard of some people just not handling niacinamide very well, so I'm not too worried about that. I know B1/biotin are sulfuric, and both cause more of the "worked" and wincing side effects. B6, I have no idea why it gives me a "crash," even when I've tried it previously in doses as low as 5mg (and also 0.6mg P5P). Strange thing too, high sulfur foods haven't been bothering me like they used to - but the B1 really, really hit me. Even had a seafood spaghetti plate last night with garlic and cream sauce, and not a single issue followed. Thanks for reading. Hope this helps some others too. TLDR: Have trouble tolerating B1, biotin, and B6 (esp. P5P), even in minimal doses. B1 and biotin produce a nearly identical reaction. Why?