TRT Side Effects and Risks

Testosterone replacement therapy is generally well tolerated when it is prescribed for genuinely low testosterone and followed up with blood tests. It is also a real medicine with real side effects. Knowing what they are, and what your doctor is watching for, is the best way to stay safe on it.

This page covers the main risks one by one, what the evidence says about the heart, and what gets monitored and roughly how often. It describes monitoring, not dosing: dose decisions belong to your doctor.

Side effects at a glance

Side effect	How common	What gets checked
Higher hematocrit (thicker blood)	Common, especially with injections	CBC
Acne and oily skin	Common	Symptoms
Lower sperm count and fertility	Very common	Discussion before starting; semen analysis if relevant
Smaller testes	Common	Symptoms
Breast tenderness or swelling	Uncommon	Estradiol, if symptoms appear
Faster male-pattern hair loss	In men already prone to it	Symptoms
Worse sleep apnea	In men with untreated apnea	Symptoms; sleep study if suspected
PSA rise or prostate growth	Small rise is common	PSA, urinary symptoms
Fluid retention, ankle swelling	Uncommon	Symptoms, blood pressure

Hematocrit: the one doctors watch most

Testosterone stimulates the bone marrow to make red blood cells. On TRT, hematocrit (the percentage of your blood made up of red cells) and hemoglobin usually rise. A small rise is expected and can even help men who were mildly anemic. A large rise makes the blood thicker, which may increase the risk of clots.

The Endocrine Society guideline advises against starting TRT if hematocrit is already high, and advises pausing or adjusting treatment if it climbs above about 54% during treatment. Shorter-acting injections with higher peaks tend to raise hematocrit more than gel or long-acting injections. Smoking, untreated sleep apnea and living at altitude can push it up further.

You usually feel nothing when hematocrit rises, which is why the CBC is non-negotiable. It is also cheap: a CBC is ₱495 at Medicard walk-in rates. If yours climbs, your doctor may change the dose, the form or the timing, or refer you for blood donation. Do not adjust anything yourself.

Estradiol

Some testosterone is converted into estradiol, a form of estrogen, by an enzyme called aromatase, mostly in fat tissue. Men need some estradiol for bone, brain and sexual health. On TRT, estradiol usually rises along with testosterone.

Most men have no symptoms from this. A minority, often men carrying more weight, notice breast tenderness, a small lump under the nipple (gynecomastia) or water retention. Guidelines do not recommend routine estradiol-lowering medicines for men on TRT, and taking them without a clear reason can cause problems of its own, including joint pain, low libido and weaker bones.

An estradiol test is ₱2,700 walk-in at Medicard. Doctors usually check it when symptoms suggest it rather than at every visit. More on the full hormone panel is in our guide to the testosterone test.

Fertility suppression

This is the side effect men are most often not told about, and it matters a lot to Filipino men who are planning a family.

Testosterone from outside the body tells the brain to stop sending LH and FSH, the signals that drive the testes. Without them, the testes make much less testosterone of their own and far fewer sperm. In many men the sperm count falls to zero. Testes also shrink, which is the visible sign of the same process.

Fertility usually recovers after stopping TRT, but it can take many months, and recovery is not certain, especially after years of use. Testosterone is not a contraceptive either, because suppression is not reliable.

If you want children in the near future, say so at your first consult. Doctors have other ways to manage low testosterone in men who want to stay fertile, and they will discuss those with you.

Acne and oily skin

Testosterone increases oil production in the skin. Acne on the back, chest and shoulders is common in the first months, more so with injections that cause higher peaks. Humid Manila weather and long hours in a work uniform do not help. It often settles as levels stabilise, and standard acne treatments from a doctor or dermatologist work. Severe or persistent acne is a reason to review the dose with your doctor.

Hair

Testosterone is converted to DHT, the hormone behind male-pattern hair loss. Men who are genetically prone to it, often with a father or grandfather who went bald early, may notice it speed up on TRT. Men without that tendency usually see little change. If hair loss runs in your family, mention it to your doctor before starting so you can watch for it early.

Sleep apnea

Obstructive sleep apnea, where the airway closes repeatedly during sleep, is common in Filipino men with a larger neck or belly, and it often goes undiagnosed. TRT can make untreated sleep apnea worse. Guidelines list severe untreated sleep apnea as a reason not to start TRT until it is managed.

Signs to mention to your doctor: loud snoring, a partner noticing you stop breathing, waking up gasping, morning headaches, and falling asleep at your desk or in traffic. Sleep apnea also lowers testosterone by itself, so treating it can sometimes improve levels without TRT. For night-shift workers, daytime sleep makes the picture harder to read, so tell your doctor about your schedule.

Prostate and PSA

Testosterone can cause a small rise in PSA (prostate-specific antigen) and slight growth of the prostate. Some older men notice more urinary frequency or a weaker stream.

TRT has not been shown to cause prostate cancer. However, an existing prostate cancer can grow faster with testosterone, which is why men over 40, or younger men with a strong family history, have PSA checked before starting and during treatment. A rise beyond what is expected, or a lump found on examination, leads to referral to a urologist. A PSA test is ₱1,990 walk-in at Medicard.

The heart: what TRAVERSE showed

For years, small studies gave mixed signals on whether testosterone raised heart attack and stroke risk. In 2023, the TRAVERSE trial answered the main question with a large, careful study.

TRAVERSE enrolled more than 5,000 men aged 45 to 80 with low testosterone and either existing heart disease or several heart risk factors. They were randomly assigned to testosterone gel or placebo gel and followed for an average of nearly three years. The results:

• Major heart events (heart attack, stroke, cardiovascular death): no increase with testosterone compared with placebo.
• Atrial fibrillation (an irregular heart rhythm): more common in the testosterone group.
• Pulmonary embolism (clot in the lung) and acute kidney injury: also more common with testosterone.

So TRAVERSE is reassuring on the biggest fear, but it does not mean testosterone is harmless for the heart. It also studied gel in men with properly diagnosed low testosterone; it does not tell us anything reassuring about high-dose steroid use. Blood pressure, lipids and heart symptoms are still part of every review. A lipid profile is ₱1,575 walk-in at Medicard.

Other effects worth knowing

• Fluid retention: mild ankle swelling, more relevant for men with heart or kidney problems.
• Mood changes: most men feel better, but a few notice irritability around peaks with shorter-acting injections.
• Skin reactions with gel: redness or itch at the application site.
• Transfer with gel: testosterone can pass to partners or children through skin contact. See types of testosterone for how the forms compare.
• Injection site soreness with injections.

What gets monitored, and roughly how often

This is guideline-based monitoring cadence, not a dosing plan. Your doctor sets the exact timing for you.

Test or check	Before starting	Early follow-up	Once stable
Total testosterone	Yes, twice	At about 3 to 6 months	About yearly
CBC (hematocrit)	Yes	At about 3 to 6 months	About yearly
PSA (men over 40 or at risk)	Yes	At about 3 to 12 months	Per usual prostate screening
Estradiol	Often	If symptoms appear	If symptoms appear
Lipids, blood pressure, weight	Yes	At follow-up	About yearly
Symptoms and side effects review	Yes	Each visit	Each visit
Sleep apnea screening questions	Yes	Each visit	Each visit

Labs can be done at Hi-Precision, Healthway, Medicard clinics or your hospital lab, and many HMO cards cover the CBC and lipid profile. For the full cost of follow-up labs, see how much TRT costs in the Philippines.

When to call your doctor sooner

Do not wait for your next scheduled visit if you notice:

• Chest pain, shortness of breath, or a racing or irregular heartbeat
• Pain, swelling or warmth in one calf
• Sudden weakness, face drooping or trouble speaking (go to the emergency room)
• New difficulty passing urine
• A breast lump
• Severe headache or vision changes

Why monitored TRT is different from steroid use

Most of the frightening stories about testosterone come from bodybuilding use, where levels are pushed far above normal, products are often unregistered or fake, and nobody checks hematocrit or PSA. Medical TRT aims for a normal level and checks your blood along the way. We cover the difference in TRT vs steroids. For the full picture from diagnosis to treatment, start with the complete TRT guide.

Frequently asked questions

Frequently asked questions

What is the most common side effect of TRT?+

A rise in hematocrit, the share of the blood made up of red cells, is the most common lab finding. Acne and oily skin are the most common side effects men notice themselves.

Does TRT cause infertility?+

TRT suppresses sperm production in most men, sometimes to zero. It usually recovers after stopping, but this can take many months and is not certain. Tell your doctor before starting if you want children.

Does TRT cause heart attacks?+

The TRAVERSE trial in 2023 found that testosterone gel did not increase heart attacks or strokes compared with placebo in men at high heart risk. It did find more atrial fibrillation, pulmonary embolism and acute kidney injury, so monitoring still matters.

Does TRT cause prostate cancer?+

It has not been shown to cause prostate cancer, but it can speed the growth of an existing cancer. That is why PSA is checked before starting and during treatment in men over 40 or at higher risk.

Will TRT make my hair fall out?+

It can speed up male-pattern hair loss in men who are already prone to it. Men without that tendency usually notice little change.

How often are blood tests needed on TRT?+

Typically before starting, again a few months in, and then about once a year when stable, with extra tests if something changes. Your doctor sets the exact timing.

Are the side effects worse with steroids than with TRT?+

Usually, yes. Steroid use pushes hormone levels far above normal, often with unregistered products and no monitoring, which makes the same risks larger and adds new ones.