Why Testosterone Results Change: Illness, Stress, Medicines and Supplements

Most people read a laboratory report in two steps: find the number, then see whether it sits inside the range. Testosterone results ask for one extra step: check the conditions around the test.

A sample taken at 4 pm while you are recovering from flu can be accurate and still tell a different story from a fasting morning sample taken when you are well. The surrounding conditions help a doctor decide whether a low result is likely to persist or whether it was shaped by that day.

Before deciding that the body is persistently short of testosterone, a doctor needs to know when the sample was taken, whether you had eaten, how you had slept, whether you were unwell, and which medicines, supplements or hormones you were using. Those details shape how testosterone results are interpreted, especially when a low number appears unexpectedly.

Start With The Testosterone Test Itself

Testosterone follows a daily rhythm. For many men with a regular sleep schedule, levels are higher in the morning and fall later in the day. In one US study, testosterone in men aged 30 to 40 was 20% to 25% higher at 8 am than at 4 pm. The difference was smaller in older men, but it could still change how a result was classified (Brambilla et al., 2009).

Eating before the blood draw can also lower the measurement. When testosterone deficiency is being investigated, current guidelines recommend fasting morning total testosterone on two separate days, using a reliable assay. Night-shift workers should tell the clinician when they usually sleep because testing by the clock may not match their body clock (Bhasin et al., 2018; European Association of Urology, 2026).

A low number alone is not a diagnosis. Doctors look for consistently low testosterone alongside compatible symptoms or signs. Start by noting the collection time, whether you had eaten, the units, the laboratory’s reference interval and whether this was the first or second test.

Illness Can Temporarily Lower The Number

A significant infection, surgery, hospital admission or flare of a chronic illness can temporarily reduce the hormone signals sent from the brain and pituitary gland to the testes. The result may be lower than the person’s usual level without proving a permanent problem with testosterone production.

European guidance advises against using a testosterone measurement taken during acute illness to diagnose testosterone deficiency. If the test has already been done, keep the report and discuss when to repeat it. There is no single waiting period that suits every infection or operation. The timing depends on how unwell you were, how fully you have recovered and why the test was ordered (European Association of Urology, 2026).

This also explains why an antibiotic does not automatically invalidate a testosterone result. The infection, fever, disrupted sleep or reduced food intake may have more influence than the antibiotic itself.

Stress Is Not One Thing

An argument before a blood draw, several weeks of poor sleep, marathon training on too little food and a severe infection may all be called stress. Biologically, they are different exposures.

Short-lived psychological stress does not have one predictable effect on testosterone. A 2024 analysis combined 21 controlled laboratory studies involving 881 people. On average, acute psychosocial stress increased rather than suppressed gonadal steroid activity, but the results varied widely. The studies covered several gonadal hormones and controlled stress tasks, so they cannot tell one person what everyday work or relationship pressure did to a testosterone result (Domes et al., 2024).

Severe energy deficit, restricted sleep and sustained heavy physical strain can reduce testosterone, particularly when they occur together. Ordinary exercise should not be presented as inherently testosterone-lowering. If stress is part of the story, describe what changed with it: sleep, food intake, training, alcohol use, medicines, sexual function or mood (Bhasin et al., 2018).

Medicines To Mention Before You Retest

Bring a complete list of prescriptions, injections, gels, over-the-counter medicines, supplements, bodybuilding products and recreational substances. Add the dose, how you take each product, how long you have used it and when you last used it. Keep taking prescribed treatment unless the clinician managing it advises a change.

Opioids and the Hormone Signal

Opioids are medicines used for pain and, in some cases, treatment of opioid dependence. Regular use can suppress the hormone signals that support testosterone production. Across 17 studies, male opioid users had lower average testosterone than non-users, although the evidence was observational and varied between studies (Bawor et al., 2015).

The medicine, dose, duration, symptoms, fertility plans and bone health all influence what a clinician checks next. Changing an opioid can affect pain control and may cause withdrawal. The Endocrine Society recognises hypogonadism as an important possible endocrine effect of long-term opioid use, while noting gaps in diagnosis and management. Speak to the prescribing clinician before reducing or stopping an opioid (Karavitaki et al., 2024).

Glucocorticoids: The Medicine and the Illness Both Count

Glucocorticoids are steroid medicines used to reduce inflammation or calm an overactive immune response. Prednisolone and dexamethasone are common examples. Systemic treatment, which reaches the whole body as a tablet or injection, can affect testosterone production, especially at higher doses or with longer use (Bhasin et al., 2018).

The illness being treated can affect the same result. Someone taking prednisolone during a severe inflammatory illness has two possible influences on the blood test: the medicine and the illness. Give the clinician the exact name, dose, route and treatment dates, and ask before making any change.

Anabolic Steroids and External Testosterone

Anabolic-androgenic steroids are drugs related to testosterone. Some people use them without medical supervision to increase muscle or performance. External testosterone may also be prescribed for a confirmed medical reason.

During use, the blood test can measure testosterone that comes from outside the body while the brain reduces the signals that normally tell the testes to make testosterone and sperm. A high or normal number on the report does not show that the body’s own production is working normally.

Anabolic steroids and external testosterone can markedly reduce or stop sperm production. Recovery after stopping can take months, sometimes longer, and may be incomplete. Tell the clinician what you used, the dose, how long you used it and the date of the last dose. Fertility plans need to be part of that conversation (Christou et al., 2017).

Other Medicines to Put on the List

Anti-androgens block testosterone’s effects, and some also reduce its production. Gonadotropin-releasing hormone medicines deliberately change the signal sent from the brain to the testes. Medicines that raise prolactin can reduce the same hormone signalling, while medicines that change sex hormone-binding globulin can make total testosterone harder to interpret. These groups do not all change the number in the same way, which is why the full medicine list is more useful than guessing which tablet caused it (Bhasin et al., 2018; European Association of Urology, 2026).

Supplements And Testosterone

A ‘testosterone booster’ is a marketing category, not a single ingredient. Products sold under that name can contain vitamins, minerals, herbs or blends, so the name on the front of the bottle tells you little about what it may do.

In 2024, researchers reviewed 52 studies covering 27 proposed boosters. Most did not increase total testosterone. The few possible benefits depended on the ingredient, dose and group being studied. Bring the bottle or a clear photograph of the ingredient list rather than relying on the marketing promise (Morgado et al., 2024).

In India, FSSAI regulations do not permit hormones or steroids in regulated health supplements. This rule describes what may be added to compliant products; it does not prove that a particular supplement raises testosterone or cannot affect a laboratory result (Food Safety and Standards Authority of India, 2016).

Biotin is vitamin B7. It appears in some multivitamins and products marketed for hair, skin and nails. High doses can interfere with laboratory tests that use biotin-based technology, producing falsely high or falsely low results depending on the assay. Tell the laboratory and clinician what you take and follow their test-specific advice on whether anything needs to be paused (US Food and Drug Administration, 2020).

How To Plan The Repeat Testosterone Test

Low testosterone results on a first test are usually checked with another fasting morning sample on a separate day. That means two blood draws, not a sample every day for a week or two. No single interval between the tests suits everyone. Illness, recovery and the reason for testing can change the timing (Bhasin et al., 2018; European Association of Urology, 2026).

The value of that second sample was clear in a multicentre Indian study of men with type 2 diabetes who had already screened positive for symptoms. The proportion with total testosterone below 300 ng/dL fell from 18.4% at the first test to 8.6% after confirmation. The study does not represent all Indian men. Abbott Healthcare funded it, and two authors were employees, which should be considered when reading the result (Unnikrishnan et al., 2024).

Before the repeat test:

• Confirm the collection time and whether you need to fast.

• Ask whether an acute illness needs more time to resolve.

• Return to your usual sleep, food and training routine where possible.

• Share every medicine, supplement, injection, gel and recent hormone exposure.

• Bring the full report, including the units and laboratory reference interval.

• Write down the symptoms, when they began and whether they have persisted.

• Mention fertility plans before discussing testosterone treatment.

If the second result is also low, a clinician may check sex hormone-binding globulin and accurately measured or calculated free testosterone, particularly when total testosterone is borderline or the carrying protein may be altered. Luteinising hormone and follicle-stimulating hormone help distinguish a testicular problem from reduced signalling by the pituitary or hypothalamus. Prolactin and other tests are added when the pattern calls for them, rather than ordered automatically for everyone (Bhasin et al., 2018; European Association of Urology, 2026).

What FOXO Primer Can Help You Prepare For

An unexpected result can leave you with disconnected details: the report, symptoms, medicines, supplements, sleep and previous tests. FOXO Primer brings medical and symptom history, lifestyle information and measured biology into a personalised Playbook reviewed with a FOXO Doctor.

FOXO Primer can help you see which questions remain open, prepare for the next clinical conversation and find an appropriate qualified professional when medical assessment or treatment is needed. Learn more about FOXO Primer.

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