We have a small group of guys, for example, that swear they do better with weekly intramuscular injections. And we have had a couple that say their testosterone is higher doing this. For example, check out what this guy wrote:
“I decided to go back to IM injections a month ago. I noticed my T levels were dropping slowly on subq…The biggest thing I notice is the huge jump in free testosterone. It’s such a big difference that I’m wondering if there’s a misreading. Not sure. Anyways, feeling great on IM injections.” 
Another poster wrote that “the differences I’ve seen on the hard-to-find models I’ve run across is that subq takes off about 40% of the peak compared to IM, which is huge — this means you have 40% lower estradiol and probably DHT, and having high estradiol is one of the worst side effects of TRT.” 
So are the above statements true? Does going to more frequent subQ injections really lower testosterone? Stories on the Forum are pretty hard to verify for consistency and timing, i.e. it is hard to know if the person measured a weekly injection at peak or trough. Lab results can vary by 20% or so pretty easily as well. That why I decided to ask Dr. Justin Saya of Defy Medical to let us know what he sees in his practice, since he deals with these issues on a daily basis. And he graciously wrote me a couple of emails with his comments starting with the following:
“We’ve seen with testosterone cypionate that smaller more frequent dosages are GREATER in cumulative effect than larger less frequent injections (i.e. Daily > TIW > BIW > once weekly). In fact, it appears most patients are able to achieve approximately the same testosterone levels with daily T cypionate dosages of 15-18mg daily (105mg – 126mg weekly) as patients who do BIW or TIW doses in the 120mg – 160mg range (i.e. 60mg BIW – 80mg BIW) and the once weekly guys doing 140mg – 180mg once weekly (though these guys have wide variation in their levels in comparison to daily/BIW/TIW over the 7 day span). Obviously results can vary and everyone is unique, but these patterns have emerged.”
I then asked him if this comment applied whether the person is doing more frequent doses IM (intramuscular) or subQ (subcutaneous)? I added that “we have guys on the forum that swear frequent subq leads to increased T over weekly IM and the other way around. I think a lot of it has to do with when they get their test done, but I’d love to get your take on it.”
“I switched to daily SubQ injections at 140mg per week. I was previously injecting IM on MWF at 140mg per week. Here are the shocking results:
IM: Testosterone,Free and Total 1151 ng/dL 348 – 1197
Free Testosterone(Direct) 20.4 pg/mL 7.2 – 24.0
SubQ: Testosterone,Free and Total 1500 ng/dL 348 – 1197
Free Testosterone(Direct) 44.3 pg/mL 7.2 – 24.0
Various members went on to discuss and postulate why this may occur. It’s important to note that for the MWF injection routine, the patient had labs on Mon (after last injection Friday- no injection Sat, Sun, or Mon prior to lab draw). The daily SC lab draw was on the day after a daily SC injection (prior to the next injection).”
This was a 25% jump by going from MWF to daily injections (although timing of labs did play some role). Dr. Saya said that his response was the following:
“This is very common with DAILY injections, regardless of if it’s SC [subcutaneous] or IM [intrasmuscular]. Most folks don’t have the desire or wherewithal to stick to a daily injection routine in the LONG term without developing ‘injection fatigue’ or becoming noncompliant. For those that can (and actually WANT to inject daily), they can often (with a few exceptions for unique cases) get away with lower cumulative weekly dosages than folks who do once weekly, twice weekly, or even three times weekly injections.
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Again, this happens with both SC and IM (I have seen both) and is really a factor of the frequency of injections more than the location/technique of injections. The complicated reasoning is due to the pharmacological parameter of TERMINAL half life, accumulation, and steady state. In simplest terms, T cyp does not reach a TRUE steady state with once weekly, twice weekly, or three times weekly dosages (although twice weekly and three times weekly come close enough for our purposes, but there is STILL variation).
On the other hand, daily injections, at least pharmacologically speaking, are capable of achieving a TRUE steady state (even less fluctuation than BIW/TIW) and consequently can often use smaller dosages. Now this comes with the obvious trade off of poking yourself 365 times per year vs 156 (three times weekly) vs 104 (twice weekly)…in the real world and clinical practice, the subjective/symptomatic difference usually isn’t large enough to outweigh the increased hassle (except for a select few, especially low SHBG fellas). Hope this isn’t too complex or technical, but hope it helps with understanding! Indeed an interesting phenomenon.”
CONCLUSION: Based on what Dr. Saya has seen in his clinical practice, we can come to the following conclusions:
1. More frequent injections, especially daily, can lead to significantly increased total testosterone levels.
2. This holds true for both IM and subQ.
3. Low SHBG guys may do particularly well with daily injections.