Low Testosterone: Symptoms, Causes and Diagnosis
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Low Testosterone: Symptoms, Causes and Diagnosis
A UK GP's guide to testosterone deficiency in men: the signs, what causes it, how it's confirmed with blood tests, and how it's treated.
Part of the Access Doctor Low Testosterone Guide.
Key fact: Low testosterone is diagnosed with blood tests, not symptoms alone. Guidance recommends two early-morning tests before treatment is considered, because many symptoms of low testosterone have other causes.
Testosterone is the main male sex hormone. It drives sex drive and erections, and helps maintain muscle, bone, energy and mood. When the body doesn’t make enough, the condition is called testosterone deficiency or hypogonadism.
Testosterone falls slowly with age, by less than 2% a year from around your 30s or 40s, which usually isn’t enough to cause problems. True deficiency is less common and usually has a cause, such as obesity, type 2 diabetes, a pituitary problem or a testicular condition.
Check Your Testosterone Level
A home finger-prick blood test, taken in the morning and analysed by an accredited UK lab.
Order a Testosterone Blood Test →Symptoms of Low Testosterone
- Low sex drive (libido)
- Erection problems, and fewer erections on waking
- Tiredness and low energy
- Low mood, irritability or poor concentration
- Loss of muscle and strength, and more body fat
- Hot flushes and sweats
- Less body and facial hair
- Breast enlargement or tenderness (gynaecomastia)
- Thinning bones (osteoporosis) and, in some men, reduced fertility
These symptoms are common and often have other causes, such as stress, depression, poor sleep, alcohol or another health condition. That’s why a blood test is needed before low testosterone can be diagnosed.
What Causes Low Testosterone?
Testicular causes
The testicles can’t make enough testosterone, for example after injury, mumps, chemotherapy or radiotherapy, or with an inherited condition such as Klinefelter syndrome.
Pituitary and brain causes
The brain doesn’t send enough signal (LH) to the testicles, for example because of a pituitary tumour, a high prolactin level or a head injury.
Lifestyle and health
Obesity, type 2 diabetes, sleep apnoea, heavy drinking and long-term illness all lower testosterone. Losing weight can raise it.
Medicines and drugs
Long-term opioid painkillers, steroid tablets, and stopping anabolic steroids used for bodybuilding can all lower testosterone.
Low testosterone that can be reversed
When low testosterone is caused by obesity, type 2 diabetes, sleep apnoea or medicines, doctors call it “functional”: the testicles and pituitary are healthy but are being held back. It often improves when the cause is treated. Losing weight, in particular, raises testosterone, and the more weight lost, the bigger the rise.
After anabolic steroids
Anabolic steroids used for bodybuilding switch off the body’s own testosterone production. After stopping, it can stay low for months, causing tiredness, low mood, low sex drive and erection problems. Production often recovers with time, but not always. If this applies to you, tell your GP openly: they can test your hormones and refer you to a specialist if needed. We don’t prescribe testosterone for this online.
What to Do If You Think You Have Low Testosterone
Get a morning blood test
Through your GP, or with a home testosterone blood test taken before 10am.
Repeat a low or borderline result
Testosterone varies from day to day, so one result isn’t enough. Test again on another morning.
See your GP with both results
Describe your symptoms and ask whether you need LH, FSH and prolactin, a blood count, PSA and a diabetes check. Mention any medicines, steroids or supplements you use.
Treat what can be treated
Weight, sleep, alcohol and medicines come first, and may be enough on their own.
Start treatment if it’s needed
Your GP or a specialist starts testosterone and sets your dose. Once you’re settled on a gel, you can order repeats from us.
How Low Testosterone Is Diagnosed
Two morning blood tests
Testosterone is highest in the morning and drops after eating, so blood is taken before 10am, ideally fasting, on two separate days.
Reading the result
BSSM guidance: total testosterone below 8 nmol/L is low, 8 to 12 nmol/L is borderline, and above 12 nmol/L is normal. Free testosterone helps when results are borderline.
Finding the cause
Your GP checks LH, FSH and prolactin to see whether the problem is in the testicles or the pituitary, plus blood count, PSA, blood sugar and cholesterol.
Specialist referral if needed
Men with very low levels, abnormal pituitary hormones or a possible underlying condition are referred to an endocrinologist or urologist.
A home test is a convenient first step. Our guide to the testosterone blood test explains the ranges and timing in detail.
Treatment for Low Testosterone
Treatment starts with the cause. Losing weight, treating sleep apnoea, cutting down on alcohol and reviewing medicines can raise testosterone on their own. If deficiency is confirmed and symptoms are troublesome, testosterone replacement therapy (TRT) may be offered.
| Type of TRT | How it’s used | Good to know |
|---|---|---|
| Gel (Testogel, Testavan, Tostran) | Applied to the skin every morning | The most common choice in the UK. Steady levels; can pass to others by skin contact |
| Short-acting injection | Into a muscle every 2 to 4 weeks | Levels rise and fall between doses |
| Long-acting injection | Into a muscle every 10 to 14 weeks | Given by a nurse or doctor |
TRT is long-term and needs regular blood tests to check testosterone, haematocrit (red blood cell level) and PSA. Read TRT side effects and monitoring. If your gel was started by a GP or specialist, you can order repeat prescriptions from our low testosterone treatment service.
Testogel 16.2mg/g Pump
For men already prescribed Testogel. 20.25mg per press.
View product →Testogel 40.5mg Sachets
Single-dose sachets for men already on Testogel.
View product →Testavan 20mg/g Gel
With a hands-free applicator. 23mg per pump.
View product →Tostran 2% Gel
Applied to the abdomen or inner thighs. 10mg per press.
View product →NHS or Private Treatment?
Testosterone treatment is available on the NHS. Your GP arranges the blood tests and usually refers you to an endocrinologist or urologist to confirm the diagnosis and start treatment. Many areas then use “shared care”, where your GP takes over prescribing and monitoring.
Private clinics can also diagnose low testosterone and start treatment, for a fee. Our service is different: we don’t diagnose or start treatment. We provide repeat prescriptions for men already established on a testosterone gel, and we keep your GP informed.
Who Shouldn’t Have Testosterone Treatment
- Men with prostate or breast cancer
- Men trying for a baby: testosterone treatment lowers sperm production
- Men with a high haematocrit (above 0.54) or a raised PSA
- Men with severe untreated sleep apnoea or uncontrolled heart failure
- Men who’ve had a heart attack or stroke in the last 6 months
Never use testosterone or anabolic steroids without a prescription. Products bought for bodybuilding are unregulated, can contain the wrong dose or substance, and can shut down your own testosterone production and fertility.
When to See Your GP
See your GP if you have symptoms of low testosterone, a low or borderline test result, or a lump or swelling in a testicle. See them urgently if low sex drive or erection problems come with severe headaches, problems with your vision, or breast discharge, which can be signs of a pituitary problem.
Already on Testosterone Treatment?
Order your repeat prescription online. A UK pharmacist prescriber checks your treatment and recent blood results. For men already prescribed testosterone only.
Start Low Testosterone Consultation →Frequently Asked Questions
What is low testosterone?
Low testosterone, also called testosterone deficiency or hypogonadism, is when the body doesn't make enough testosterone. It's confirmed with two early-morning blood tests and can cause low sex drive, erection problems, tiredness and loss of muscle.
What are the first signs of low testosterone?
Low sex drive, fewer morning erections and erection problems are often the first signs, along with tiredness and low mood. These symptoms have many other causes, so a blood test is needed to check.
At what age does testosterone start to drop?
Testosterone falls slowly from around your 30s or 40s, by less than 2% a year. This gradual fall usually doesn't cause symptoms on its own; true deficiency usually has another cause, such as obesity or diabetes.
Can low testosterone be reversed without treatment?
Sometimes. Losing weight, treating sleep apnoea, cutting down on alcohol and changing medicines such as opioid painkillers can raise testosterone. If an underlying cause is treated, levels may return to normal.
Is low testosterone the same as the male menopause?
Not exactly. The term 'male menopause' is sometimes used for symptoms in midlife, but they're often caused by lifestyle or psychological factors rather than hormones. Only some men have genuinely low testosterone.
Can low testosterone cause erectile dysfunction?
Yes, it can contribute, especially with low sex drive. But most erection problems have other causes, such as narrowed blood vessels, so both are usually checked.
Does low testosterone affect fertility?
It can, depending on the cause. Testosterone treatment itself lowers sperm production, so men who want children are usually offered different treatment by a specialist.
What should I do if I think I have low testosterone?
Start with a blood test before 10am, through your GP or a home kit. If the result is low or borderline, repeat it on another morning and take both results to your GP, who can look for a cause and refer you if needed.
Can anabolic steroids cause low testosterone?
Yes. Anabolic steroids switch off the body's own testosterone production, and it can stay low for months after stopping. It often recovers, but not always. Tell your GP, who can test your hormones and refer you to a specialist.
References
- Hackett G, et al. British Society for Sexual Medicine. British Society for Sexual Medicine guidelines on male adult testosterone deficiency, with statements for practice. World Journal of Men's Health, 2023. bssm.org.uk
- NHS South Yorkshire ICB. Shared care protocol: testosterone for male hypogonadism (Doncaster). December 2025. southyorkshire.icb.nhs.uk
- NHS. Male menopause and low testosterone. nhs.uk
- MHRA Drug Safety Update. Topical testosterone (Testogel): risk of harm to children following accidental exposure. January 2023. gov.uk
- Electronic Medicines Compendium. Testogel 16.2mg/g gel: Summary of Product Characteristics. medicines.org.uk
Medical disclaimer: This article is for informational purposes only and does not constitute medical advice. Prescription medicines require a consultation before they can be dispensed. Always consult a qualified healthcare professional for diagnosis and treatment. In a medical emergency, call 999.
