Anastrozole is an anti-estrogen medication officially classified as an Aromatase Inhibitor (AI). The compound was first developed in the fight against breast cancer, and while highly successful, it is also used in low testosterone treatment. The use of AI’s in Testosterone Replacement Therapy (TRT) is to combat the possible side effects of testosterone use. Anastrozole does have the ability to stimulate natural testosterone production to a degree and some physicians will use it for that purpose, but side effect prevention is its primary purpose of use in TRT. However, as with all medications, side effects of Anastrozole are possible. Fortunately, most TRT patients will find they are easily avoidable when the AI is used in the right doses at the right time. Unfortunately, as with all medications the side effects of Anastrozole will be a problem for some men despite responsible use due to a poor genetic response. This is a factor that holds true with all medications including simple over the counter items such as Aspirin.

Anastrozole & Fatigue:

One of the most common side effects of Anastrozole is fatigue and general weakness. This medication is designed to promote a dramatic reduction in serum estrogen levels and when levels fall to a low point, weakness and fatigue is what you’re left with. However, this should not be an issue for the TRT patient. This side effect is well-known among breast cancer patients as they typically need a daily dosing of upwards of 1mg per day, but no TRT patient will need near this amount. The breast cancer patient often attempts to eradicate estrogen in the body, while the TRT patient has the simple goal of optimizing his levels. If weakness and fatigue are a problem and you are supplementing with exogenous testosterone, if testosterone levels are optimal odds are strong the Anastrozole dose is too high. If your estrogen levels fall too low, you will feel weak and fatigued regardless of how high your testosterone levels are.

Anastrozole & Bones:

One of the more worrisome side effects of Anastrozole is in its ability to reduce bone mineral content. A reduction in bone mineral content could potentially lead to a greater susceptibility to osteoporosis. For the breast cancer patient, this is simply a risk that has to be accepted. There are things that can be done with diet and lifestyle that will offer protection, but they will be dramatically lowering serum estrogen levels in order to starve out the cancer making the tradeoff more than justified. As for the TRT patient, while this side effect of Anastrozole is often warned against, low doses of the AI along with optimized testosterone levels should have no ill effect. In fact, those who have healthy testosterone levels greatly reduce their risk of osteoporosis.

Anastrozole & Cholesterol:

The side effects of Anastrozole can include a reduction in HDL cholesterol (good cholesterol); however, this is very unlikely. The use of this AI alone does not appear to have a significant affect on lipids in most cases, but this can change when it’s used with testosterone. There seems to be a conjoined relationship between Anastrozole and testosterone that creates a reduction in HDL levels. For example, data has shown that the use of testosterone alone in therapeutic or supraphysiological doses does not have a significant impact on lipids. There may be an HDL reduction with some performance level doses, but it should not be severe. However, data also shows that when such use is conjoined with an AI, HDL cholesterol may be reduced by as much as 25%.

As some negative lipid values can come about due to the side effects of Anastrozole, a cholesterol friendly lifestyle is important. However, this is an important aspect of a healthy life with or without TRT. Diet’s should be rich in omega fatty acids, low in simple sugars and saturated fats and should be accompanied by regular cardiovascular activity. When these things are done, baring no underlying issue, there is absolutely no reason you should have lipid issues.

General Side Effects of Anastrozole:

The side effects of Anastrozole will prove most problematic in TRT patients when they use too much too often. Approximately 25% of all TRT patients will not need any AI’s as their estradiol levels will not increase despite testosterone use. If your estradiol levels are optimal and you use an AI, often you will succumb to the weakness and fatigue mentioned prior as well as joint pain. Hot flashes and headaches are also very commonplace; in fact, some notice their immune system becomes much weaker with long-term low serum levels. Other possible side effects of Anastrozole include depression and nausea and/or vomiting; however, such effects are extremely rare and typically indicate a poor genetic response to the medication.