Your weekly testosterone injection
Testosterone cypionate. How to take it, what we watch, and when to call us. One section matters more than the rest: when to get your blood drawn.
This is the guide we give patients starting testosterone. You're welcome to read it before you're a patient. We'd rather you knew.
The short version
- Draw exactly what your prescription says. Not a number from a chart, a video, or a friend at the gym.
- Same day every week.
- Get your blood drawn halfway between injections. Drawing too close to either one gives your provider a misleading number.
- We recheck your blood regularly. Testosterone changes more than your testosterone level, so we watch a few things and adjust as we go.
- Testosterone lowers your sperm count. If you might want children, tell us before your first injection.
- Chest pain, breathlessness, or a swollen painful leg means emergency care, not a message to us.
When to get help
- Chest pain or pressure.
- Shortness of breath.
- Pain or swelling in one leg.
- Sudden weakness, numbness, confusion or trouble speaking.
What you're takingWhere yours comes from, and what we're aiming for
Testosterone cypionate, given as a weekly injection either just under the skin or into the muscle.
Where yours comes from. Testosterone comes as commercially manufactured products, which we sometimes send to your local pharmacy, and as compounded preparations made by a compounding pharmacy. Your prescription label tells you which you have, and your visit notes give your clinician’s reasoning.
If yours is compounded, it’s prepared to your prescription rather than produced to a fixed commercial standard, and compounded medications are not FDA‑approved. Either way, the instruction below is the same: go by your own label.
We’re aiming for a testosterone level in a healthy range, with your symptoms resolved.
Why higher isn't better, and why the number alone isn't the target More
Pushing your level above the normal range adds risk without adding benefit, and if yours lands there we’ll bring your dose down.
But the number on its own isn’t the target either. If your level looks fine and you still feel flat, that’s a conversation, not a shrug.
Most people notice energy, mood and sex drive shift first, over weeks. Changes in body composition come later, and only with the training and eating to support them.
How to take itYour dose, the injection steps, and where they go
The strength in your vial and the number of units you draw are set for you. Another man on testosterone may have a different strength and a different number on his label, so a dose from a chart, a video, a forum, or a friend at the gym is not your dose. If his vial is a different strength, copying his number puts the wrong amount of drug in your syringe.
This matters most with a compounded preparation, where the strength is made to your prescription rather than to a fixed commercial standard. But it holds either way.
Your provider adjusts your dose over time based on your blood tests and your symptoms. Every change comes from them and arrives on your label. If your label is unclear, or the amount doesn’t look like what you expected, stop and message us before you inject.
Set a repeating reminder and write down the date each time.
Your provider will walk you through this at your first visit. The written version, so you have it:
- Wash your hands. Wipe the top of the vial with an alcohol swab, and let it dry.
- Put the drawing-up needle on the syringe. Two needles are standard: a wider one to draw with, because it pulls the oil through faster, and a thinner one to inject with, because it hurts less.
- Pull air into the syringe to about the same amount as your dose.
- Push that air into the vial. Insert the needle through the rubber top and press the plunger. This replaces the volume you’re about to remove, so the liquid comes out easily instead of fighting a vacuum.
- Turn the vial upside down, keeping the needle in, and check the needle tip is sitting in the liquid rather than up in the air space. Draw your dose slowly.
- Swap to the injecting needle. This is the thinner of the two, and a thinner needle is noticeably more comfortable going in. The wide one is for getting the oil out of the vial quickly, nothing else.
- Get the air out. Point the needle up, tap the barrel so bubbles rise, and press the plunger gently until liquid appears at the tip. What’s left in the syringe should be medication and nothing else.
- Clean the injection site with a fresh alcohol swab, let it dry, then inject.
- Straight into the sharps container, which is the hard plastic bin made for used needles. New needles and a new syringe every time. Never share them.
Keep everything sterile as you go. If a needle touches anything other than the vial top or your cleaned skin, replace it.
Your prescription will say whether yours goes under the skin (subcutaneous) or into the muscle (intramuscular).
Under the skin goes into the belly, staying a couple of inches clear of your navel, or the upper outer thigh.
Into the muscle goes into the outer thigh, or the upper outer quarter of your buttock. To find that spot, picture one buttock divided into four squares and use only the top outer one, well away from the middle. Your provider will show you the first time.
Move to a different spot, and alternate sides, each week.
Doubling up won’t get you there faster. It pushes your level higher than we want it, thickens your blood, and can hold up your refill while we sort it out. If you miss a dose, take it as soon as you remember and go back to your normal day. Don’t stack two.
Your blood tests, and the timing mistake nearly everyone makesWhen to get drawn, and what each test is for
Your testosterone level isn’t flat. It peaks in the days after an injection and drifts down until the next one. Draw at the peak and you’ll look artificially high. Draw right before your next injection and you’ll look low. Either way your provider ends up adjusting your dose against a number that doesn’t represent your week.
Halfway between is the number that does. So:
- Injecting weekly? Get drawn 3 to 4 days after your injection.
- Injecting every two weeks? Get drawn about a week after, not on the day the next one is due.
- Any other schedule? Count the days between your injections and aim for the middle. Ask us if you’re unsure.
What we test, what each one is for, and the timing for creams and tablets More
Same principle, different timing, if you’re on another form: cream is 2 to 5 hours after you apply it, and the oral form is 3 to 5 hours after your morning dose. Whatever you do, tell the lab or write down when your last dose was, so your provider can read the result in context.
What we check. Your testosterone level, of course. Also your hematocrit, which is the percentage of your blood made up of red cells, because testosterone raises it. Estradiol, a form of estrogen that testosterone partly converts into. Liver function. And a prostate blood test called PSA, depending on your age.
And LH, which does two different jobs depending on when we measure it. LH is the signal your brain sends to your testicles telling them to make testosterone.
Before you start, it tells us where the problem is. If LH is high, your brain is shouting and your testicles aren’t responding. If it’s low or normal while your testosterone is low, the signal itself is the problem. Those point to different causes and sometimes different treatments.
Once you’re on treatment, your brain sees testosterone arriving from outside and stops asking for more, so LH usually drops. That’s expected, not a problem, and it’s the same mechanism behind the effect on sperm production described further down. It’s worth knowing that this varies between men, so a low LH supports the picture rather than proving anything on its own.
How often. More at the start, while we’re finding your dose, then less once you’re steady. Your provider will tell you when your next set is due.
Thicker blood, and why we watch itWhat we do if it climbs
Testosterone makes your body produce more red blood cells. Past a point, thicker blood moves less easily and raises the risk of clots, so we check it every time.
If it climbs further than we want, we act. Usually that means lowering your dose, and sometimes pausing a refill until a repeat test comes back down. Your provider will talk you through what applies to you and why.
If we do pause a refill, it isn’t administrative and it isn’t a judgment about you. It’s us not letting a number keep climbing while you carry on as normal.
Fertility, and why to decide before you startSperm count, and the alternative that preserves it
For most men it recovers after stopping, but recovery can take a long time and it isn’t guaranteed.
If you might want children, now or in a few years or you’re not sure, say so before your first injection. Enclomiphene raises your own testosterone instead of replacing it, and it doesn’t shut down sperm production the same way. It’s a real alternative, not a consolation prize, and switching later is harder than choosing now.
Side effectsThe common ones, and what to tell us about
Common. Acne and oilier skin, holding onto fluid, soreness at the injection site, mood changes, and shrinking of the testicles.
Four things worth telling us about, even though they aren't emergencies More
- Breast tenderness or swelling. Testosterone partly converts into estrogen, and if that balance tips we can address it.
- Snoring that’s noticeably worse, or daytime sleepiness. Testosterone can worsen sleep apnea, where your breathing pauses during sleep.
- Sleep that’s gone poor.
- Irritability that’s out of character.
A note on your prostateWhen we check PSA, and why it changes after year one
PSA is a blood test for the prostate. Here’s when we check it, and why the schedule changes after your first year.
Before you start, if you’re 40 or older, so we have your own starting number to compare against later. If prostate cancer runs in your family, or you’re Black, that baseline matters from 40 rather than later, because risk starts earlier.
Once during your first year on treatment. This is the window where a change would most likely show up, so it’s the one check we do because you’re on testosterone.
After that, it goes back to normal. Whether you keep having PSA tests, and how often, becomes the same decision any man your age would make with his doctor. It stops being a testosterone question. For most men in their late fifties and sixties that’s a genuine choice with arguments on both sides, and past seventy the usual advice is that routine testing does more harm than good. Your provider will talk it through with you rather than just ordering it.
If a result does rise, either above the usual threshold or by a meaningful amount from your own starting number, we repeat the test first, since a single PSA can move for reasons that have nothing to do with cancer. If it holds, we refer you to a urologist and talk with you about whether to pause testosterone while that’s looked into.
Things worth knowingStorage, other prescribers, and the cream
- Tell your primary care provider and any other prescriber that you’re on testosterone. It belongs on your medication list.
- Keep it out of reach of children, and store at room temperature away from light.
- If you’re ever prescribed the cream instead, testosterone transfers by skin contact. Cover the area and wash your hands. Children and partners can absorb it.
- This works alongside your life, not instead of it. Sleep, training, protein and alcohol all move your results. Testosterone won’t outrun any of them.
Follow-ups and refillsBooking, and messaging us between visits
Book your follow-up before you run out, and get your blood drawn far enough ahead that the results are back for your visit. Missing blood tests is the most common reason a refill stalls.
Message us any time between visits. You don’t need an appointment to ask a question or report something that feels off.
Where this comes fromOur sources, in plain language
- Side effects, warnings and how to take it: the FDA-approved prescribing information for testosterone cypionate.
- When to get your blood drawn: Endocrine Society guidance, which advises measuring midway between injections for this form of testosterone.
- Prostate monitoring: American Urological Association and Endocrine Society guidance on monitoring men receiving testosterone therapy, which is a separate question from population screening advice.
- Fertility: research on how testosterone therapy suppresses the brain’s signal to the testicles, and what recovery looks like after stopping.
Ask us for the full references any time. We’d rather show our work than have you take our word for it.