T Nation

How Long for T Levels to Drop After Last Injection?


Curious how long for test levels to drop after last injection. I have searched various forums and answers are all over the place. Any ideas?


Depends on the type of test. The “half life” of test cypionate is supposed to be 7 or 8 days, meaning that you’d have half the initial amount after a week or so that you had initially. I’m not sure if the amount in your blood follows an exact curve like that, but that’s the approximation.

Look up “graph of testosterone injection after injection”


Thx brianb for reply. Yes I know that but surely you dont just lose it all in 3 days but I could be wrong. My total was like 1490 few weeks ago and last injection yestrday. Fall back to 350 in 3-4 days?


What did you inject? Cyp? Enth? Prop?


Test E thx for reply


The half life for E is 4.5-5 days, so thirty days before it’s completely out of your system.

5 days - 50%, 10 days - 25%, 15 days - 12.5%, 20 days - 6.25%, 25 days - 3.125%, 30 days - 1.5625%

It’s maths bitches.

@yogi, thought you would appreciate this.


never thought of it like that! You’re the man appreciate it bro


So if I go without my next shot to drop my levels how long do I need to wait before taking my blood test? Because at first he started me on 200mg of test cyp for trt every two weeks but my levels were all over the place & I felt a huge drop waiting two weeks for my next shot so I started doing 100mg per week instead but I can feel that it’s not enough! So considering my last shot was at least 8 days ago(on the 10th) of 50mg (to attempt to lower my levels) how long should I wait before taking my blood test to ensure its low enough to justify and increase to 200 per week? (I’m probably not gonna take another shot until after my blood test)


So does that mean after 8-10 days your test levels have dropped alot?