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Men's Hormones and TRT: Side Effects, Fertility, Heart Risk and Monitoring, Checked Against the Evidence

The questions men ask once low testosterone is on the table: what the side effects are, how to protect fertility, what the TRAVERSE trial showed about the heart, which blood tests to expect, and whether boosters work. Answers from FDA labels, AUA and Endocrine Society guidelines, and trials.

By Kymata Labs EditorialLast verified October 11, 2026

Medical review pending. Written by our editorial team from the studies and documents cited below; a credentialed clinician has not reviewed it yet. Educational only, not medical advice.

Key takeaways

  • FDA-approved testosterone is for men with low testosterone plus an associated medical condition; in June 2026 the FDA asked makers to drop the label statement that safety and efficacy in age-related low testosterone are not established [1].
  • In TRAVERSE, 5,246 men at high heart risk had major heart events at 7.0% on testosterone gel vs 7.3% on placebo, with more atrial fibrillation, acute kidney injury and pulmonary embolism [2].
  • Rising hematocrit is the most common side effect; the AUA says a hematocrit of 54% or higher on treatment warrants action [3].
  • Testosterone suppresses sperm production, so the AUA says not to prescribe it to men trying to conceive; it lists hCG, SERMs such as clomiphene and aromatase inhibitors as alternatives, on low-grade evidence [3].
  • Of 50 testosterone booster products reviewed, only 24.8% had published data showing a testosterone increase [4].

Guides in this hub

  1. TRT Side Effects: Hematocrit, Acne, Sleep Apnea, Fertility and What Guidelines Do About EachThicker blood (a rising hematocrit) is the most common side effect of testosterone therapy, and injections raise it most. Acne, worse sleep apnea in some men, lower sperm counts and a small rise in blood pressure are the others that labels and guidelines flag.
  2. TRT and Fertility: hCG, Clomiphene, Enclomiphene and What the AUA Guidelines AllowTestosterone therapy can shut down sperm production, so AUA guidelines say not to prescribe it to men trying to conceive. They list hCG, SERMs such as clomiphene, and aromatase inhibitors as fertility-sparing options, all on low-grade evidence and mostly off-label.
  3. Testosterone and Heart Risk: What the TRAVERSE Trial Found and What the FDA ChangedFor a decade testosterone labels warned about heart attacks and strokes. TRAVERSE, the FDA-required safety trial, found no increase in major heart events, and in February 2025 the FDA removed that boxed-warning language and added a blood-pressure warning. Atrial fibrillation, kidney injury and lung clots were more common on testosterone.
  4. TRT Blood Tests: What Gets Checked Before and During Testosterone Therapy, and WhenBefore testosterone therapy: two morning testosterone tests, LH, hematocrit and, over 40, PSA. After: a testosterone level once the dose settles, hematocrit within the first months, then repeat tests every 6 to 12 months. Here is the schedule the two main US guidelines describe, and when to draw blood on each form.
  5. Clomiphene for Men: How It Raises Testosterone, What Studies Show, and the Off-Label CaveatsClomiphene citrate is FDA-approved only for ovulation problems in women, yet clinicians prescribe it off-label to men with low testosterone who want to keep their fertility. The studies are mostly observational, and estradiol and vision changes need watching.
  6. TRT vs Natural Testosterone Boosters: Which Supplements Have Trials, and How Big the Effects AreMost supplements sold as testosterone boosters have no trial behind their claim. Ashwagandha and tongkat ali have small positive trials, zinc helps mainly when you are low in it, vitamin D trials found no effect, and D-aspartic acid did nothing or lowered testosterone.

Start here

Each guide below answers one question with primary sources: FDA labels on DailyMed, randomized trials and meta-analyses on PubMed, and the American Urological Association (AUA) and Endocrine Society guidelines. Figures carry the source they came from.

This hub picks up after the diagnosis. For symptoms and the two-morning-test rule, see low testosterone symptoms; for prices and providers, see what TRT costs online and online TRT compared.

How we grade the evidence

We rank randomized trials and meta-analyses above observational studies, and FDA labels above marketing. Guideline statements are quoted with their own strength rating where it matters, because several of the fertility options rest on low-grade evidence.

Commercial vs compounded testosterone

Many online clinics prescribe compounded testosterone. The AUA conditionally recommends commercially manufactured products over compounded testosterone when possible, because compounded preparations are made without direct FDA oversight and testing has found wide swings in potency [3]. Ask any clinic which form it prescribes and which pharmacy fills it.

Partners we link to

  • ARSYNL RxPaid linkOnline men's hormone care from Arsynl LLC (Dover, DE). Its menu (checked Oct 11, 2026) lists testosterone cypionate, a testosterone HypoSpray, enclomiphene and an at-home men's hormone blood test. Its product pages say compounded medications are not FDA-approved; its clinicians decide eligibility at intake.See ARSYNL Rx's TRT options (opens in new tab)

    Partner links may earn us a commission. Learn more

  • MangoRxPaid linkOnline TRT starting at $149 a month (checked Oct 11, 2026), with a lab panel at LabCorp or Quest, a video visit and a full refund if you don't qualify. Its FAQ calls the $149 a testing kit and does not publish the ongoing medication price, so confirm the recurring charge before you pay.See MangoRx's TRT plan (opens in new tab)

    Partner links may earn us a commission. Learn more

Regulatory and legal notes

  • Testosterone products are FDA-approved only for men who lack or have low testosterone together with an associated medical condition, such as testicular failure or a pituitary or hypothalamic problem [1].
  • On Feb 28, 2025 the FDA told makers of all testosterone products to add TRAVERSE results, remove boxed-warning language about increased cardiovascular risk, and add a warning that testosterone can raise blood pressure [5].
  • In June 2026 the FDA requested removal of the limitation-of-use statement on age-related hypogonadism and revised prostate safety information; labels update product by product [1].
  • Dietary supplements, including testosterone boosters, are not approved by the FDA before they are marketed [6].

References

  1. [1]Testosterone Information (updated June 23, 2026). U.S. Food and Drug Administration, 2026.
  2. [2]Cardiovascular Safety of Testosterone-Replacement Therapy. N Engl J Med, 2023. PMID 37326322
  3. [3]Evaluation and Management of Testosterone Deficiency (2024). American Urological Association, 2024.
  4. [4]'Testosterone Boosting' Supplements Composition and Claims Are not Supported by the Academic Literature. World J Mens Health, 2020. PMID 31385468
  5. [5]FDA issues class-wide labeling changes for testosterone products (Feb 28, 2025). U.S. Food and Drug Administration, 2025.
  6. [6]Questions and Answers on Dietary Supplements. U.S. Food and Drug Administration, 2026.

Dietary supplements are not intended to diagnose, treat, cure or prevent any disease, and these statements have not been evaluated by the FDA. Prescription options need a licensed clinician. Talk to your clinician or pharmacist before starting anything new, especially if you take prescription medicines, are pregnant or breastfeeding.

Keep reading: Testosterone (TRT) and men's hormones

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Previous in this topicTRT Nation Review (2026): $99.99/mo, Real Cost and the CatchTRT Nation costs $378.97 to start and about $1,457.87 in year one on its lowest plan.Next in this topicTRT Side Effects: Hematocrit, Acne, Sleep Apnea, Fertility and What Guidelines Do About EachThicker blood (a rising hematocrit) is the most common side effect of testosterone therapy, and injections raise it most.TRT and Fertility: hCG, Clomiphene, Enclomiphene and What the AUA Guidelines AllowTestosterone therapy can shut down sperm production, so AUA guidelines say not to prescribe it to men trying to conceive.Testosterone and Heart Risk: What the TRAVERSE Trial Found and What the FDA ChangedFor a decade testosterone labels warned about heart attacks and strokes.TRT Blood Tests: What Gets Checked Before and During Testosterone Therapy, and WhenBefore testosterone therapy: two morning testosterone tests, LH, hematocrit and, over 40, PSA.

TRT cost compared →Telehealth cost calculator →