Hi Nancy @nancysav, I've been taking 1200 mg na-R-ALA daily (600mg morning/evening) for quite a few years along with other supplements. I haven't experienced any facial flushing from the ALA but did find a research paper that mentions it.

"Results
The 600 mg dose was well tolerated. At the 800 mg dose, one subject had an intolerable flushing sensation. At the 1,200 mg dose, two subjects had intolerable upper gastrointestinal side effects and one subject had an intolerable flushing sensation. Subjects taking gastrointestinal prophylaxis medications had no upper gastrointestinal side effects.

Conclusion
High-dose ALA is not completely tolerated by the elderly. These preliminary data suggest that gastrointestinal prophylaxis may improve tolerability."
-- Tolerability in the elderly population of high-dose alpha lipoic acid: a potential antioxidant therapy for the eye: https://pmc.ncbi.nlm.nih.gov/articles/PMC5047711/

GoodRX has a list of medications that can cause the flushing along with some other causes - https://www.goodrx.com/health-topic/dermatology/why-is-my-face-red,