HCG also gives me anxiety.
hCG is closely related to TSH. High amounts of hCG, often seen in pregnancy and probably in injection (5,000 - 10,000 IU), can cause hyperthyroidism (increase in T3, T4 and shutdown of TSH) although not at the level seen in Graves disease.
I don't think the anxiety for me has any relation to HCG's potential influence on thyroid levels, because 1) as noted above it requires extremely high dosages to cause hyperthyroidism, and 2) the hcg anxiety feels very different than when my t3 dosage was too high. In addition, 3) every time I've tested my hormones on and off hcg, my thyroid levels are pretty much identical. I've been on t3-only thyroid replacement, TRT, and other hormones for 17 years. That being said, I haven't come across why hcg causes anxiety. Of course it's probably related to the cascade of hormonal changes... DS3 noted in one of the first posts here it is due to unique effects of HCG on the CNS.
I've played around with the dose of HCG and it seems any dose gives some anxiety, but there is a sweet spot where side effects are minimized. It seems 350 iu 3x/week is best for me. Day 1 mild anxiety but very tolerable. Day 2 anxiety is gone if I sleep well.
500iu was too much- spiked T and estrogens too high and ruined sleep. Doing the shot in the AM, day 1 anxiety was very high, short term memory issues, cognitive and mood issues (tolerable, but very noticeable). Day 2 I would feel amazing with T accelerating probably. Day 3 quite good still. At that dose, I felt overall pretty good the first month due to sky high T levels and estrogens that hadn't caught up to me. Then they caught up by the 2nd month and I cut back the dose to 350.
250iu was too low of a dose. I just felt crappy all the time. Sort of low mood persistently.
So 350 it is for now. For me at least, the response is quite different at the different dosage levels. Not just a linear change in anxiety or mood with dose. A very different effect altogether.
I will say I unexpectedly learned that HGH (genotropin or norditropin in my case) reduces anxiety. So when doing the
500 iu hcg, doing 1.8 units norditropin helped offset the anxiety. However, it was not sustainable due to cost and the fact it was dramatically increasing my blood pressure.