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.
This can be countered to an extent. You can increase the dosage towards the middle and later parts of taking it to increase the positive effects. You can also take a period of time away from the drug, cycling off for a bit to give your body time to recover before getting back to it again. Be aware that the more you take a day, the less results you will get added to through the additional dosage. So for example, taking 50mg a day adds a lot. Adding 50mg a day improves the results, but not by much. Adding 50mg more for 150mg a day adds slightly more, but it is typically not worth the negative side effects to your health for only marginal improvements. Studies conducted on the drug helps to back up this assertion, postulating that 100mgs/day is perfect for Anadrol cycling.