It should be noted that in theory if one was to consistently suppress your natural estrogen levels for a long period of time, this would negatively impact your health, including your cholesterol. Due to the ability of Letrozole- to inhibit estrogen so much, this should definitely be a concern to most users. However the research that has focused on the relationship between use of letrozole and cholesterol levels is rather inconsistent in it's findings. Many studies have concluded that the compound is detrimental to both a user's HDL and LDL cholesterol levels, while other research has found no link. Obviously individuals are best served to monitor their cholesterol while using any compound via blood tests however barring that, letrozole should simply not be run for extended periods of time if at all possible. Doing so could cause serious medical complications.
Along with the issues related to blood lipids is the fact that many users complain that their libido is dramatically reduced when using the compound. This is related to the fact that estrogen is partly responsible for the regulation of an individual's sex drive. Since Letrozole- is so potent it can often drive estrogen levels too low and this inhibits a user's libido. To avoid this users can lower dosages, but some anecdotally report that even extremely low doses of the drug can cause problems. If this is the case a less potent compound such as exemestane or anastrozole may be a more appropriate option.
Stacking – Trenbolone only cycles are not recommended for a couple of reasons. While significant gains can be realized using trenbolone alone, the compound really shines when stacked with testosterone. It is particularly effective with Anadrol or Dianabol. Another reason trenbolone should be stacked with other compounds is because of estradiol issues. Not only does trenbolone not convert into estradiol (aromatise ), but at the same time, it suppresses the body’s natural production of testosterone, which is the source of estradiol in men. This means that a user may actually experience an unacceptable decrease in estrogen levels that can lead to problems with libido, joints and mood. Stacking trenbolone with another steroid that has a high estrogen conversion rate will prevent this situation. HCG and other compounds can be used during the cycle to prevent estrogen related issues.
In a study of 1,685 patients treated with CPA, elevated liver enzymes were seen in 10% of patients at a dosage of 50 mg/day and in 20% of patients at a dosage of greater than 100 mg/day.  A study of 2,506 patients given 18–136 mg/day for less than 48 months per patient reported a rate of %.   In a trial of 89 prostate cancer patients who received high-dose CPA for 4 years, there were elevated liver enzymes in % of the patients.  Yet another study of 105 patients found a hepatotoxicity rate of %, with serious hepatic injury occurring in %.  In 2002, it was reported that there were 18 case reports of CPA-associated hepatitis in the medical literature, with 6 of the cases resulting in death.  In addition, a review article cited a report of 96 instances of hepatotoxicity that were attributed to CPA, and 33 of these instances resulted in death.  Moreover, a 2014 review found that 15 cases specifically of CPA-induced fulminant (sudden-onset and severe) liver failure had been reported to date, with only one of these cases not resulting in death.  As such, the prognosis of CPA-induced liver failure is death.