I recommend avoiding HCG for at least the first two weeks after the recovery period has started. By the start of the recovery period, I mean the time point where androgen levels from steroids taken during the cycle have fallen sufficiently to allow LH production to begin to resume. HCG use during this early phase can interfere with recovery of LH. I’m not saying it’s impossible to recover LH production while using HCG, but HCG use impairs the process.
HCG use during recovery does make it impossible to determine by “feel” whether recovery of LH is occurring. LH could be near zero while testosterone is normal or high-normal.
Ideally, a blood test for LH is taken at about 2-4 weeks into the recovery to establish for a fact whether LH production has recovered. This is optional: many don’t do it but instead go simply from how they feel and perform, which can be a good basis if HCG was not used during recovery.
When confident for either of these reasons that a good recovery has occurred, then a bridging, or between cycle, use of HCG can begin. I recommend starting with a modest amount, such as about 250-275 IU 3x/week. At this usage level, a 5000 IU vial lasts 6 weeks.
If you already have been using Femara Letrozole or another aromatase inhibitor when off-cycle and have found a dosage suitable for you to maintain ideal estradiol levels (low 20’s pg/mL), then at first use the aromatase inhibitor at that same dosage while using HCG. If you don’t already have information on your estradiol levels, then at first don’t add an aromatase inhibitor. Save it for when you have blood test results.
HCG use between cycles is one time that blood work really should be taken more seriously than it commonly is. If wanting to use HCG between cycles, I strongly recommend against guesswork. If it’s gotten wrong, then LH production will be shut down not only during the cycles, but in most of the off weeks as well. For the hypothalamus and pituitary, it can become the equivalent of using oral anabolic steroid almost every week of the year.
In most cases when estradiol is kept at a good level, normal LH production can be maintained while using HCG at about 200-275 IU 3x/week. This can provide substantially higher testosterone levels, typically high-normal, than when HCG is not used. The benefit between cycles can be noticeable, with no adverse side effects at all.
About 2 weeks into HCG use, LH and estradiol should be tested. If estradiol is outside the low 20’s pg/mL range, aromatase use should be adjusted. If estradiol is good but LH is low, HCG use should be decreased, for example to 250 IU twice per week.
Where estradiol and LH levels are good, optionally HCG dosage may be increased. There’s no reason to go past about 1500 IU/week, as further benefit past that level is unlikely. Retesting should be performed after each adjustment of HCG dose.