Men's wing · 4 labels read 2026-08-15

Testosterone side effects, from the labels rather than the clinic

Name: Testosterone Side Effects, from the FDA Labels
Creator: Iacob Pastina

Ask any TRT clinic about thick blood and you will hear 54 percent. We read 4 FDA-approved testosterone labels and 0 of them print a number. Every one says a version of "if hematocrit becomes elevated", and they disagree on how often to look, from approximately every 3 months to "periodically" with no interval given. The 54 percent belongs to the American Urological Association guideline, which is worth following and is a different kind of document. Below: what the labels do say, what TRAVERSE actually found, how fast fertility goes and how far it comes back, and the one boxed warning still standing on a testosterone product.

What are testosterone side effects?

Testosterone replacement side effects are the unwanted effects of raising circulating testosterone above what the body is producing, plus a second group belonging to the delivery method. Exogenous testosterone suppresses the pituitary signals that drive the testes, which is why sperm production falls, and it stimulates red blood cell production, which is why hematocrit rises and why every FDA label instructs that hematocrit be checked before treatment starts. The two groups need separating when reading any list: erythrocytosis and fertility suppression follow the hormone whatever the product, while application-site reactions and transfer of the drug to another person by skin contact belong to the gels alone.

Compounded testosterone and compounded enclomiphene, dispensed by several telehealth platforms, are not FDA-approved products and carry no adverse-reaction table of the kind below. What enclomiphene is and who prescribes it.

Erythrocytosis: four labels, three cadences, zero numbers

Testosterone raises red cell mass. Every label says so, every label tells you to check, and the instructions diverge from there. Each quote below is verbatim from the posted label, read 2026-08-15.

Product	How often the label says to check	Number given
AndroGel 1.62% (gel)label posted 2025-10-22	Before starting, again at 3 to 6 months, then annually	None
Xyosted (testosterone enanthate auto-injector)label posted 2025-07-01	Before starting, then approximately every 3 months	None
Jatenzo (oral testosterone undecanoate)label posted 2025-09-30	Before starting, then approximately every 3 months	None
Depo-Testosterone (testosterone cypionate injection)label posted 2025-09-29	Periodically, with no interval given	None

Where 54 percent comes from: American Urological Association, Testosterone Deficiency guideline, read 2026-08-15. It recommends a baseline hematocrit below 50 percent before starting and withholding therapy above that until the cause is explained, then measuring every 6 to 12 months, or sooner depending on prior values to maintain hematocrit below 54 percent. It notes polycythemia is generally defined as a hematocrit above 52 percent. Following it is good practice. Describing it as what the label requires is wrong, and it is the sentence to listen for during an intake call.

On the AndroGel trial itself, hematocrit or hemoglobin increased was reported in 2.1 percent of the 234 treated patients against 0 percent of the 40 on placebo, and two men left the open-label period because of it.

Fertility: how fast it goes, and how far it comes back

The label states the mechanism plainly: "With large doses of exogenous androgens, including AndroGel 1.62%, spermatogenesis may be suppressed through feedback inhibition of pituitary FSH possibly leading to adverse effects on semen parameters including sperm count." The speed is in the AUA guideline's discussion: Testosterone enanthate 200 mg intramuscularly every week lowered intratesticular testosterone by 94 percent within 3 weeks. In the WHO Task Force trial, 271 healthy fertile men on 200 mg of testosterone enanthate weekly reached adequate suppression of spermatogenesis in 98 percent of subjects, with a mean time to azoospermia of 120 days.

Recovery, pooled from contraception studies in 1,549 healthy men who stopped, measured as sperm concentration returning above 20 million per mL:

67%

within 6 months

90%

within 12 months

96%

within 16 months

100%

within 24 months

Read the caveat the guideline attaches rather than the reassuring headline. Those men were fertile at baseline, with normal testosterone and two semen samples above 20 million per mL to enter the study, so the figures may not generalise to a man who started TRT because something was already wrong. Around 10 percent did not recover sperm in the ejaculate until the second year. The guideline's own statements are unambiguous: Statement 23: "Exogenous testosterone therapy should not be prescribed to men who are currently trying to conceive." (Strong Recommendation, Evidence Level Grade A)

That is the entire reason enclomiphene exists on this site. It raises testosterone by stimulating the pituitary rather than replacing the hormone, so it does not switch off the signal that drives sperm production. For a man who wants children later, that is a different decision from picking a cheaper injection. Of the 5 platforms in our men's wing, 5 offer injections and 3 offer a topical.

The cardiovascular question, and what TRAVERSE actually found

TRAVERSE was the trial regulators asked for. 5,246 men aged 45 to 80 with existing cardiovascular disease or a high risk of it, randomised to testosterone gel or placebo gel, mean treatment 21.7 months and mean follow-up 33 months. The primary endpoint was a first event of cardiovascular death, nonfatal myocardial infarction, or nonfatal stroke.

Testosterone

182 men

Placebo

7.3%

190 men

Hazard ratio 0.96 (95% CI 0.78 to 1.17), which met the trial's noninferiority margin. Lincoff AM et al, Cardiovascular Safety of Testosterone-Replacement Therapy, N Engl J Med 2023. Then the sentence the marketing pages omit: the trial observed a higher incidence of atrial fibrillation, acute kidney injury, pulmonary embolism in the testosterone arm. The AndroGel label carries the venous numbers from that trial directly: venous thromboembolism 1.7 percent against 1.2 on placebo, deep vein thrombosis 0.6 against 0.5, and pulmonary embolism 0.9 against 0.5. Noninferior on heart attacks is a narrower claim than safe.

The labels then moved, and you can watch it happen in the labels themselves rather than in a press release. The Jatenzo label's recent major changes table, read 2026-08-15, records these:

Boxed Warning, Increases in Blood PressureRemoved 03/2025
Contraindications, men with age related hypogonadismRemoved 03/2025
Warnings and Precautions, Cardiovascular Risk (5.3)Removed 03/2025
Warnings and Precautions, Venous Thromboembolism (5.2)Revised 03/2025
Warnings and Precautions, Blood Pressure Increases (5.4)Revised 03/2025

The Xyosted SPL, RECENT MAJOR CHANGES table carries the matching line for the boxed warning on the same date, which is how you can tell this was a class-wide action rather than one manufacturer's decision. Blood pressure did not disappear from the labels: it moved from the boxed warning into warnings and precautions. The AndroGel label still reports a mean rise of 1.9 over 1.3 mm Hg at week 16 on ambulatory monitoring, and 3 over 2.2 in men already taking antihypertensives.

The gels carry a boxed warning about the people around you

Of the testosterone labels read for this page, one still carries a boxed warning, and it is about somebody other than the patient. The AndroGel 1.62% (testosterone gel) label heads it WARNING: SECONDARY EXPOSURE TO TESTOSTERONE:

"Virilization has been reported in children who were secondarily exposed to testosterone gel. Children should avoid contact with unwashed or unclothed application sites in men using testosterone gel."

The warnings section is more specific than the box. Reported signs in secondarily exposed children have included enlargement of the penis or clitoris, development of pubic hair, increased erections and libido, aggressive behavior and advanced bone age. In most reported cases these regressed once exposure stopped. In a few, enlarged genitalia did not fully return to age-appropriate size and bone age remained modestly ahead. The label attributes increased transfer risk in some of those cases to application instructions not being followed.

This is a route decision with a household in it. Injections and pellets have no dosed skin to touch and carry no such warning. In our men's wing, 3 of 5 platforms offer a cream or gel, and pellets are offered by 1. The full men's rankings, scored and graded.

The label's adverse reaction table

182-day randomized double-blind placebo-controlled period, 234 hypogonadal men on AndroGel 1.62% and 40 on placebo. Reported in more than 2 percent of patients and more frequent than placebo.

Reaction	AndroGel 1.62% (n=234)	Placebo (n=40)
PSA increased	11.1%(26)	0%
Emotional lability	2.6%(6)	0%
Hypertension	2.1%(5)	0%
Hematocrit or hemoglobin increased	2.1%(5)	0%
Contact dermatitis	2.1%(5)	0%

The placebo arm held 40 men against 234 on the drug, so one placebo patient would move that column by more than two points and the zeros are thinner than they look. 10.7 percent of treated patients (25 men) stopped because of an adverse reaction, and 17 of those were a rising PSA. Application site reactions were reported in 2 of 234 men, or 0.9 percent.

What a competent clinic monitors, and what to ask before you pay

The AndroGel label's own list, in its own order: serum testosterone, prostate specific antigen, hemoglobin, hematocrit, liver function tests and lipid concentrations, checked periodically. The AUA adds a baseline hemoglobin and hematocrit before therapy is offered at all, graded a strong recommendation, and psa measured in men over 40 years of age before starting therapy.

Four questions worth asking an intake nurse. How often do you recheck hematocrit, and what number makes you stop. Do you draw a baseline PSA before the first shot. What happens to my prescription if a lab comes back out of range, in writing. And if I want children in the next five years, what are you offering me instead of testosterone. A clinic that cannot answer the fourth one is not equipped to hold that conversation.

Seek urgent care for chest pain, shortness of breath, or pain, swelling, warmth or redness in one leg. Those track the venous thromboembolism warning the labels carry and the pulmonary embolism signal TRAVERSE reported. Palpitations that will not settle are worth a same-day call given the atrial fibrillation finding in the same trial.

Who on our roster prescribes what

Monitoring is the thing a price comparison cannot show you, so read the review page before the checkout page. Our men's wing carries 5 platforms:

Defy Medicalscore 7.6, Transparency Grade C· offers injection, cream, pellet, oral
Hone Healthscore 7.5, Transparency Grade C· offers injection, cream, oral, patch
PeterMDscore 7, Transparency Grade C· offers injection
MangoRxscore 7, Transparency Grade C· offers injection, oral
Maximusscore 6.5, Transparency Grade D· offers oral, injection, cream

Scores come from our published methodology and no platform pays for a position in it. The men's rankings, the fertility-preserving alternative, and how the Transparency Grade is built.

FAQ

Testosterone side effects, answered

What are the side effects of testosterone replacement therapy?

From the AndroGel 1.62% (testosterone gel) label, the reactions reported in more than 2 percent of patients during the 234-patient double-blind period, each at 0 percent in the 40-patient placebo arm, were PSA increased at 11.1 percent, emotional lability at 2.6 percent, hypertension at 2.1 percent, hematocrit or hemoglobin increased at 2.1 percent, and contact dermatitis at 2.1 percent. The warnings section adds the ones that matter more than the frequencies: erythrocytosis, suppression of sperm production, blood pressure increases, worsening of benign prostatic hyperplasia, sleep apnea in men with risk factors, and for the gels, transfer of testosterone to a partner or child by skin contact.

What hematocrit level is too high on TRT?

No FDA testosterone label names one. We read 4 of them and all 4 use a version of "if hematocrit becomes elevated", with no number attached. The 54 percent figure clinics quote comes from the American Urological Association guideline, which recommends measuring every 6 to 12 months, or sooner depending on prior values to maintain hematocrit below 54 percent, recommends a baseline below 50 percent before starting, and notes that polycythemia is generally defined as a hematocrit above 52 percent. That is a guideline recommendation rather than a labelling requirement, and the distinction matters when a clinic tells you its protocol follows the label.

Does TRT cause infertility, and is it reversible?

Suppression is expected and is on the label. The AndroGel 1.62% (testosterone gel) label states that spermatogenesis "may be suppressed through feedback inhibition of pituitary FSH possibly leading to adverse effects on semen parameters including sperm count". On speed, the AUA guideline cites a study in which 200 mg of intramuscular testosterone enanthate weekly lowered intratesticular testosterone by 94 percent within 3 weeks. On reversibility, it pools 1,549 healthy men from contraception studies: sperm concentration returned above 20 million per mL in 67 percent within 6 months, 90 percent within 12, and 100 percent within 24. Those men were fertile at baseline, so the figures may not generalise to men who started with a fertility problem, and the guideline says so.

Does testosterone cause heart attacks?

The trial built to answer that question found it did not, within its own bounds. TRAVERSE randomised 5,246 men aged 45 to 80 with existing cardiovascular disease or high risk of it to testosterone gel or placebo gel. A first event of cardiovascular death, nonfatal myocardial infarction or nonfatal stroke occurred in 182 men on testosterone (7 percent) against 190 on placebo (7.3 percent), hazard ratio 0.96 (95% CI 0.78 to 1.17), meeting the noninferiority margin. The same trial reported a higher incidence of atrial fibrillation, acute kidney injury, pulmonary embolism in the testosterone arm, and those three findings are the part that gets dropped from the summary.

Can testosterone gel transfer to my partner or my kids?

That is the boxed warning on the gel, and it is the only boxed warning left on the testosterone products we read. The AndroGel 1.62% (testosterone gel) label carries "WARNING: SECONDARY EXPOSURE TO TESTOSTERONE": virilization has been reported in children secondarily exposed to testosterone gel, and children should avoid contact with unwashed or unclothed application sites. The label's warnings section records that in most reported cases the signs regressed after exposure stopped, and that in a few cases enlarged genitalia did not fully return to age-appropriate size. Injections and pellets do not carry this warning, because there is no dosed skin to touch.

What should a TRT clinic be monitoring?

The AndroGel 1.62% (testosterone gel) label's own list is serum testosterone, prostate specific antigen, hemoglobin, hematocrit, liver function tests and lipid concentrations, checked periodically. On hematocrit specifically the four labels we read give three different cadences, from approximately every 3 months to "periodically" with no interval at all. The AUA adds PSA in men over 40 before starting, and a baseline hemoglobin and hematocrit before therapy is offered at all, which it grades a strong recommendation. A clinic that ships testosterone after a single lab panel and never asks for another one is running below every one of those documents.

Sources

AndroGel 1.62% (testosterone gel) prescribing information, Ascend Therapeutics U.S., LLC, DailyMed (label posted 2025-10-22, read 2026-08-15).
Xyosted (testosterone enanthate auto-injector) prescribing information, DailyMed (label posted 2025-07-01).
Jatenzo (oral testosterone undecanoate) prescribing information, DailyMed (label posted 2025-09-30).
Depo-Testosterone (testosterone cypionate injection) prescribing information, DailyMed (label posted 2025-09-29).
Lincoff AM et al, Cardiovascular Safety of Testosterone-Replacement Therapy, N Engl J Med 2023 (PMID 37326322)
American Urological Association, Testosterone Deficiency guideline (read 2026-08-15).
Bhasin et al, Testosterone Therapy in Men With Hypogonadism, Endocrine Society clinical practice guideline, J Clin Endocrinol Metab 2018 (PMID 29562364)

This is general information, not medical advice. Testosterone is a controlled prescription medicine and whether it is right for you, at which dose and by which route, is a decision for you and a licensed clinician. Written and reviewed by Iacob Pastina. Back to the Safety Center.