Arimidex (Anastrozole)

Anastrozole, sold as Arimidex, is the aromatase inhibitor most people reach for first. It blocks the conversion of testosterone to estrogen rather than blocking estrogen at the receptor, which makes it effective and predictable - and easy to overshoot.

The estradiol problem

Because it is a blunt enzyme blocker, anastrozole will happily take estradiol to a level that causes aching joints, a flat affect and a vanished sex drive. That is the single most common complaint in this category, and it is entirely avoidable: measure, adjust, re-measure. A 0.5mg dose twice a week is a common starting point precisely because a whole tablet is frequently more than anyone needs on a moderate dose of testosterone.

Verification

• Label names anastrozole and mg per tablet - genuine Arimidex is a small 1mg tablet.
• Sealed bottle, printed batch and expiry, tablets intact.
• Storage cool and dry, away from pets and children.
• Sourcing matters: this is a widely prescribed drug, so the counterfeit risk is lower but not zero.

Quick answers

How much arimidex on cycle?

0.25-0.5 mg every other day is the standard starting window on 300-500 mg of testosterone - not daily, not 1 mg. Titrate against bloodwork, not anxiety. The anastrozole guide has the full titration logic.

What does crashed estrogen feel like?

Dry joints, flat libido, sharp mood drop, sleep gone - the AI overshot. Arimidex clears fast (two-day half-life), so it corrects within a week of stopping; the AI comparison explains why some switch to the steroidal option for a softer landing.

Do I need an AI on a testosterone-only cycle?

Some do not. Genetics and dose decide - get estradiol tested at week six before pre-committing to a protocol. Prevention guidance lives in the gyno prevention guide.