Short answer: “Test 400” is the name of injectable testosterone sold for bodybuilding, labeled as 400 mg per milliliter. It is not an FDA-approved medicine. And 400 mg of testosterone a week is about twice the highest weekly-equivalent dose in testosterone cypionate labeling (calculated): a steroid-cycle amount, not testosterone replacement therapy (TRT). [1,2]
Key takeaways
- The FDA drug database lists no product called Test 400 and no testosterone injection at 400 mg/mL. [1]
- Labeled cypionate dosing works out to at most about 200 mg a week (calculated); 400 mg a week is twice that. [2]
- No study tested 400 mg a week. At 300 and 600 mg a week, testosterone rose far above normal, hemoglobin rose and HDL cholesterol fell. [3]
- High doses can suppress sperm production, and the impact on fertility may be irreversible. [4]
Important safety information
Testosterone is a Schedule III controlled substance. Its labeling reports heart attack, stroke, liver injury and serious psychiatric reactions with steroid misuse, and dependence at doses above the therapeutic range. Seek urgent care for chest pain, sudden shortness of breath, leg pain or swelling, or signs of a stroke. [2]
What is Test 400?
Test 400 is a product name, not a dose or a medicine. It, “testosterone 400” and “testosterone 400 mg” usually describe injectable testosterone said to contain 400 mg per milliliter. The FDA database has no product by that name, no approved testosterone at 400 mg/mL, and no approved product that blends several testosterone esters. [1]
Approved injections are far less concentrated: cypionate at 100 or 200 mg/mL, and enanthate at 200 mg/mL or as weekly autoinjector doses. “Test E 400”, “testosterone blend 400mg” and the Spanish “testosterona 400” name the same kind of unapproved product. [1]
Test 400 is typically obtained outside the regulated US pharmacy supply, so its content and sterility usually cannot be verified. A “test 400 injection” is anabolic steroid use, not treatment; see how TRT differs from anabolic steroid use. [2]
Testosterone is a prescription-only controlled substance
Testosterone is FDA-approved for men whose low testosterone is caused by a medical condition of the testes, pituitary or hypothalamus. Its safety and effectiveness for age-related low testosterone have not been established, and the cypionate labeling states it has not been shown to be safe and effective for enhancing athletic performance and should not be used for that purpose. [2,5]
Is 400 mg of testosterone a week too much?
Yes. 400 mg a week is not a TRT dose. It is about twice the highest weekly-equivalent dose in testosterone cypionate labeling and four to five times the Endocrine Society’s typical starting dose of 75 to 100 mg a week (calculated). Doses this high push testosterone far above the normal range. [2,3,6]
That is also the honest answer to “test 400 dosage” or “400 mg testosterone cypionate per week”: neither is a medical dose. A prescriber treats diagnosed low testosterone with an approved product, adjusting the dose from blood tests. The table compares weekly amounts with labeling and with the main dose-response study, done in healthy men aged 18 to 35 whose own testosterone was suppressed. [1,3,6]
| Weekly amount | Compared with labeled cypionate dosing | Nearest arm in the dose-response study |
|---|---|---|
| 75–100 mg | Typical guideline starting dose [6] | 125 mg arm: nadir testosterone 542 ng/dL [3] |
| About 200 mg | Highest labeled amount, 400 mg every 2 weeks (calculated) [2] | No 200 mg arm |
| 300 mg | About 1.5 times the labeled maximum (calculated) [2] | 300 mg arm: nadir 1,345 ng/dL; fat-free mass +5.2 kg [3] |
| 400 mg | About 2 times the labeled maximum (calculated) [2] | No 400 mg arm tested [3] |
| 600 mg | About 3 times the labeled maximum (calculated) [2] | 600 mg arm: nadir 2,370 ng/dL; fat-free mass +7.9 kg [3] |
For the next dose down, see what the study found at 300 mg a week. [3]
What happens at 400 mg a week?
No trial has measured 400 mg a week. In the 300 and 600 mg arms of a 20-week trial, nadir testosterone averaged 1,345 and 2,370 ng/dL, lean mass rose, and hemoglobin went up and HDL cholesterol went down as testosterone rose. Sexual function and mood did not change significantly at any dose. [3]
The nadir is the lowest level between injections. Guidelines adjust a TRT dose when mid-interval testosterone exceeds 600 ng/dL; the 300 mg nadir was more than twice that (calculated). [3,6]
Searches for “400 mg testosterone per week results” or “test 400 results” usually concern bodybuilding cycles, a dose this trial did not test. [3] For a fuller comparison of high doses, see how 400 mg and 1 gram a week compare with physiologic TRT.
Risks and monitoring at doses above the TRT range
Risks rise with dose: a high red blood cell count, higher blood pressure, lower HDL cholesterol, blood clots, reduced sperm production that may not recover, and, with misuse, serious heart, liver and psychiatric reactions and dependence. [2,3,4]
- Red blood cells. Hemoglobin rises with dose. Hematocrit above 54% counts as erythrocytosis, and one weekly product’s label advises checking hematocrit about every 3 months. [4,6]
- Blood pressure and clots. Testosterone can increase blood pressure, raising cardiovascular risk over time; deep vein thrombosis and pulmonary embolism have been reported. [2]
- Fertility. Large doses can suppress sperm production, and the impact on fertility may be irreversible. [4]
- Other effects. Fluid retention, breast enlargement, worse sleep apnea, and depression. [2,4]
- Misuse. Reported reactions include cardiac arrest, cardiomyopathy, liver toxicity, severe mood disorders and infertility; they come from voluntary reports, so frequency is unknown. Dependence has not been documented at approved doses for approved uses. [2]
Signs your dose may be too high
Acne, ankle swelling, rising blood pressure or irritability can appear on testosterone; a rising hematocrit shows up only on a blood test. Your clinician confirms with labs before changing a dose. [2,6]
What determines your weekly TRT dose
A real TRT dose starts with a diagnosis: symptoms plus testosterone below the normal range on morning tests from at least two separate days. The prescriber then uses an approved product within its labeled range and adjusts toward a mid-normal level. [2,6]
- Diagnosis and goals. Symptoms, the cause of low testosterone, and whether you plan to have children soon. [6]
- Formulation. Cypionate and enanthate injections cause peaks and valleys that may bring fluctuating symptoms; gels cause less erythrocytosis. [6]
- Monitoring. Testosterone, hematocrit, prostate cancer risk and symptoms, especially in the first year. [6]
- Safety evidence. In 2025 the FDA added TRAVERSE trial results and blood pressure warnings to testosterone labels; that trial studied replacement doses only. [5]
Benefits when dosing stays in range
In men 65 or older with low testosterone, treatment improved sexual activity, desire and erectile function and slightly improved mood, but not vitality. In the dose-response trial, higher doses did not improve sexual function or mood. [3,7]
Where do peptides fit in?
Peptides are not a reason to raise a testosterone dose; ask your clinician what evidence supports any add-on.
When TRT may not be appropriate
Testosterone is contraindicated in men with breast cancer, known or suspected prostate cancer, or serious heart, liver or kidney disease. Guidelines also advise against starting it in the situations below. [2,6]
- Plans to father a child in the near term. [6]
- A prostate nodule, or PSA above 4 ng/mL, without urological evaluation. [6]
- High hematocrit, untreated severe sleep apnea or severe urinary symptoms. [6]
- Uncontrolled heart failure, or a heart attack or stroke within the last 6 months. [6]
- A blood-clotting disorder (thrombophilia), or uncontrolled high blood pressure. [2,6]
Men with a past history of prostate or breast cancer should discuss any testosterone treatment with their specialist.
Finding your safe TRT dose
The right TRT dose is the lowest one that brings testosterone into the normal range and relieves symptoms, set and monitored by a prescriber. [2,6]
At Advanced TRT Clinic, a licensed physician reviews your history and lab results before any treatment is considered. If you are using Test 400, have been offered it, or think you have low testosterone, book a consultation for an evaluation with lab work.
