You've decided to start testosterone replacement therapy. Bloods came back low, your prescriber's signed you off, the first dose is in. Now what? The first month is the bit no one really talks about — the marketing tells you you'll feel reborn, the cautious doctors warn it'll take six months. Reality sits somewhere in between, and the curve is different for different formulations.
This article is what we tell every patient who's about to start. It's specific to NZ — funded formulations, BPAC framework, lab-timing pragmatics — and to the men we actually see, not an idealised journey. If you're not yet on TRT and trying to decide, the signs-you-might-need-TRT and how-to-get-TRT-in-NZ articles are the place to start.
Before day one
A few things worth doing in the week before you start:
- Have your baseline bloods. Total + free testosterone, SHBG, LH, FSH, prolactin, oestradiol, FBC (including haematocrit), lipids, liver function, HbA1c, ferritin, PSA if you're over 40. These are the anchor measurements every future result will be compared against.
- Know your formulation and the plan. Are you on testogel daily, Sustanon every 3 weeks, cypionate weekly, or Reandron 10–14 weekly? Each has a different onset curve, and what you expect to feel in week 1 is different for each.
- Take starting photos and write down current symptoms. Sleep, libido, morning erections, energy through the day, training response, mood, brain fog, motivation. Score each 1–10. In 12 weeks you'll forget where you started — write it down.
- Stock the basics if you're self-injecting. Syringes, needles, sharps container, alcohol swabs. Your prescriber will tell you what's appropriate for your protocol.
Week 1: the start
The earliest physiological effects begin within days, but most aren't subjectively obvious yet.
- First 48 hours: Some men report a noticeable "lift" in mood and motivation almost immediately. This is real for fast-onset esters (Sustanon's propionate component, gel applied that morning), and largely a placebo effect for slower esters like cypionate where the dose hasn't peaked yet. Both are fine. Don't read too much into them either way.
- Day 3–5: Cypionate is rising toward peak. Gel users are at steady state. Sustanon is at peak. Most men describe this as "feeling more like themselves" — not a transformation, more a quietening of the background flatness they'd grown used to.
- Day 6–7: Sleep can change first. Often deeper and more refreshing. Morning erections — if they'd disappeared — can return earlier than anyone expects. Libido may shift noticeably; energy and motivation usually a few weeks behind it.
What's normal in week 1:
- Mild injection-site soreness for 24–48 hours after an IM shot
- Slight increase in libido or morning erections (or no change yet — both fine)
- Subtle mood lift
- No change in body composition (nothing visible happens this fast)
What's not normal in week 1, contact your prescriber:
- A red, hot, expanding injection-site reaction (possible infection)
- Persistent dizziness or chest pain
- A sudden severe headache or visual disturbance
Week 2: settling in
By week 2 the early excitement (or anti-climax) has passed and the protocol is finding its rhythm.
- Sleep, libido, mood — small but consistent improvements for most men. Not the cinematic before-and-after you see online — more "I notice I'm not dragging through the afternoon like I was."
- Cypionate users approaching the second injection. The pre-dose trough is the first hint of what your level looks like at the low point of the week.
- Sustanon users at the steepest part of the curve. Some men feel a noticeable drop in the latter half of week 2 — this is the propionate and phenylpropionate clearing while the decanoate is still doing the heavy lifting.
- Gel users at steady state. If absorption is going to be a problem (skin variability, transfer concerns, daily-application adherence) you'll see it now.
What to track this week: how your sleep and mood feel before your next dose. This is the trough experience. If you feel flat or symptomatic right before your next shot, it tells the prescriber something useful about interval and dose.
Week 3: the second wave
Most men describe week 3 as the start of the real effects — energy and motivation start to feel different, not just sleep and libido.
- Energy through the workday. The 3 PM crash you'd written off as "getting older" often softens. Training tolerance improves before training performance does — you find you can do the same workout with less recovery.
- Cognitive clarity. Brain fog is a frequently-described low-T symptom and it lifts. You'll usually notice it as "things feel less effortful" rather than a dramatic before-and-after.
- Mood baseline. The flatness or low-grade irritability that many men carry into low-T treatment starts to lift around now.
- Side effects, if they're coming, show up by week 3. Mild acne is the most common. A slight increase in haematocrit is the most important (you won't feel it — the bloods at 6–8 weeks will catch it).
- Sustanon users approaching their second injection. The full cycle is now visible.
What to track: training response, energy across the day, any side effects (acne, water retention, sleep disruption, mood swings).
Week 4: emerging steady state
By week 4 most formulations are at or approaching steady state, and the first month's gains start to feel real.
- Body composition — nothing visible yet. Muscle gain takes longer than you'd think, even on TRT. What's happening underneath is the receptor and protein-synthesis machinery preparing for it; what shows in the mirror is months out.
- Training performance — usually noticeably better by week 4. More strength on the bar, faster recovery between sessions.
- Libido and sexual function — usually well-improved by now if testosterone was the cause. If it isn't tracking with mood and energy gains, you may have a secondary cause — vascular, psychological or medication-related — that the workup will surface.
- Sleep — most men report deeper, more restorative sleep by week 4. If sleep is worse, dose may be too high (high oestradiol can disrupt sleep), or you may have undiagnosed sleep apnoea that TRT can unmask.
What to track for the 6–8 week review: the same symptom score you took at baseline. Mood, libido, energy, sleep, training, motivation. Honest scoring — overstating gains makes dose adjustment harder.
At 6–8 weeks: first bloods
The first review trough bloods are the most important set of numbers in your TRT journey. By 6–8 weeks the formulation is at steady state and we can see what the protocol is actually delivering.
What gets checked:
- Total testosterone (trough) — drawn just before your next dose. Target: lower half to mid normal reference range (around 15–20 nmol/L for most men, depending on age and symptoms).
- Free testosterone — calculated from total + SHBG. Often more clinically meaningful than total.
- Oestradiol — should be in the normal range. Elevated oestradiol drives mood, water retention and sleep symptoms.
- Haematocrit (FBC) — the single most important monitoring number. If climbing toward the upper limit, dose may need reduction or venesection planning.
- LH / FSH — confirmed suppressed, as expected on TRT.
- PSA if 40+ — baseline trend.
If symptoms are good and bloods are in range, you stay the course. If bloods are still low despite good symptoms — usually nothing to do. If bloods are in range but symptoms haven't improved — workup widens (oestradiol, thyroid, sleep, medications, vascular). If bloods are above range — dose reduces.
What "settled" feels like — 3 months in
The first month is the start of the curve, not its plateau. Most men describe a 3-month feel-better window:
- Month 1: Sleep, libido, mood early gains.
- Month 2: Energy, motivation, training response.
- Month 3: Cognitive clarity stabilises, body composition starts to shift visibly, you feel like yourself.
What this means practically: don't make big judgements about whether TRT is "working" before you've finished month 3 and had your second set of bloods. The first month is signal, not verdict.
What can go wrong in the first month
A short list of the most common early hiccups and what they usually mean:
- High oestradiol symptoms (mood lability, nipple sensitivity, water retention, libido oddly not improving) — typically dose too high or aromatising fast; usually fixed by dose adjustment, occasionally needs an aromatase inhibitor short-term.
- Acne on the back / shoulders — sebum response to testosterone, usually mild, settles by month 2–3.
- Trouble sleeping — high oestradiol or starting dose too high. Bloods will clarify.
- No subjective change at all — possible the dose is too low, possible the diagnosis was wrong (low testosterone wasn't actually driving your symptoms), possible the formulation isn't matching your absorption. Bloods at 6–8 weeks tell us which.
- Worsening symptoms — uncommon, but a flag. Dose, formulation or diagnosis revisit. Talk to your prescriber.
- Anxiety / irritability — sometimes dose-related (high oestradiol), sometimes the receptor system adjusting. Usually settles. If pronounced, dose review.
FAQ
How fast will I feel different? Most men feel small shifts in sleep, mood and libido within the first 1–2 weeks. The bigger, sustained changes (energy, training, body composition) build over months 1–3. Anyone telling you it's day-three transformation is selling marketing, not medicine.
Should I train differently in the first month? No. Train as you normally would. The strength and recovery gains will arrive on their own — pushing harder before recovery has improved is the classic early-TRT injury pattern.
When can I make the second injection? Per your protocol's interval — don't adjust on your own. Weekly cypionate means weekly, not when you "feel like you need it."
Do I have to inject in the same place every time? No — rotating sites (alternate thighs / glutes / abdomen for SC) is recommended to reduce localised soreness.
Can I drink in the first month? Yes, in normal moderation. Heavy alcohol affects testosterone, liver and sleep — its own problem — but a couple of beers won't affect the protocol.
What if I miss a dose? For weekly cypionate or fortnightly Sustanon, take the missed dose as soon as you remember and resume the schedule from there. For Reandron the timing is more sensitive — contact your prescriber. For daily gel, just resume tomorrow.
Do I tell my GP? Yes. Your GP needs to know what medications you're on, especially for cardiovascular and surgical context. We send a standard letter to your GP at the start of treatment if you'd like us to.
What we do at Enhanced Men
- Pre-start consult: confirm diagnosis, choose the formulation, set the protocol, organise baseline bloods if you don't have recent ones
- Self-injection training if you're going the SC route
- 6–8 week review: trough bloods + clinical review, dose adjusted if needed
- 3-month full review: full repeat panel, comprehensive look at progress
- GP letter at start and at 3 months so your wider medical team is in the loop
The consult is the cost. The medication is on the standard NZ Pharmac pathway.
References (NZ-specific)
- BPAC NZ — Prescribing testosterone in ageing males (2024)
- New Zealand Formulary — testosterone esters monograph (nzf.org.nz)
- Medsafe NZ — Depo-Testosterone data sheet
- Endocrine Society — Testosterone Therapy in Men with Hypogonadism: Clinical Practice Guideline
This article is general health information and does not replace personalised medical advice. The first month on TRT can vary considerably between men — your subjective experience and your bloodwork are both data, and your prescriber will use both to set the right course for you.