Clinically reviewed by Dr. Ponlawat Pitsuwan, Physician, Doctor Bangkok. Last reviewed: July 2026
Low testosterone can cause reduced sex drive, weaker erections, fatigue, low mood and loss of muscle. Sexual symptoms point most strongly to a hormone problem, while tiredness and mood changes have many other causes. A blood test is the only way to confirm it.
Plenty of men come to see me convinced their testosterone is low because they feel tired and flat. Sometimes they are right. Just as often, the real culprit is poor sleep, stress, alcohol, an underactive thyroid or low mood, all of which produce very similar symptoms. The trick is knowing which signs genuinely point to a hormone problem and which are red herrings.
This article walks through the symptoms of low testosterone, separates the more telling ones from the vaguer ones, and explains the common causes. If you want the bigger picture on testing and treatment, see our main guide to testosterone therapy in Bangkok.
The symptoms that point most strongly to low testosterone
Some symptoms are far more specific than others. When men have these, I am more inclined to test and to trust a low result.
Sexual symptoms
Reduced sex drive, fewer spontaneous morning erections, and weaker erections are the symptoms most closely linked to low testosterone. A noticeable drop in libido in particular tends to track with hormone levels more reliably than fatigue does. Where erections are the main problem, they may need their own assessment; our guide to erectile dysfunction treatment in Bangkok covers this.
Physical changes
Loss of muscle mass, increased body fat around the middle, reduced body hair, breast tenderness or swelling, and smaller, softer testicles can all accompany genuine deficiency. These build slowly and are easy to miss until you look back over a year or two.
The vaguer symptoms that overlap with everything else
Fatigue, low mood, irritability, poor concentration, disturbed sleep and low motivation are all commonly blamed on testosterone. They can be caused by low levels, but they are also the everyday symptoms of stress, overwork, jet lag, alcohol and depression. On their own, without any of the more specific signs, they rarely turn out to be a hormone problem. This is why I never diagnose low testosterone on symptoms alone.
What causes low testosterone
Low testosterone falls into two broad groups. In one, the testicles themselves are not producing enough, from ageing, injury, infection, certain medications or genetic conditions. In the other, the problem is upstream in the pituitary gland or hypothalamus, which signal the testicles to work. Distinguishing the two guides both the diagnosis and the treatment.
Lifestyle and reversible causes
Obesity is one of the most common and most reversible contributors, since excess fat tissue lowers testosterone. Heavy alcohol use, chronic stress, poor sleep, untreated sleep apnoea, some painkillers and, importantly, anabolic steroid use can all suppress your own production. The good news is that several of these can be improved.
Why a blood test is essential
Because symptoms overlap so heavily with other conditions, the only way to know is a blood test, confirmed on a second morning sample. A proper work-up also checks for the mimics such as thyroid problems, anaemia and diabetes. You can read what is involved in our guide to the testosterone test in Bangkok, and to understand the results, see normal testosterone levels by age.
When to see a doctor
See a doctor if you have reduced libido or erection problems, especially alongside fatigue or mood changes, or if any of these symptoms are affecting your relationship or daily life. Get prompt review for breast swelling or tenderness, testicular changes, or symptoms in a younger man. A general health check-up can help find the cause.
Recognise these symptoms? At Doctor Bangkok, a 24/7 walk-in clinic in Sukhumvit, a physician can test your testosterone and look for the other causes too. Read our full testosterone therapy guide or contact us to arrange a visit.
Frequently asked questions
Can I have low testosterone but still feel fine?
Yes. Some men have low readings without troublesome symptoms, and treatment is usually not needed in that situation. Treatment is considered when a low level and matching symptoms occur together.
Is tiredness alone a sign of low testosterone?
Rarely on its own. Fatigue has many causes, including poor sleep, stress, thyroid problems and low mood. It is more meaningful when it appears alongside reduced libido or other specific signs.
Can losing weight raise my testosterone?
Often yes. Excess body fat lowers testosterone, and weight loss can improve levels for some men. That is why we look at lifestyle factors before assuming lifelong treatment is needed.
Do anabolic steroids cause low testosterone?
Yes. Anabolic steroid use suppresses your body’s own testosterone production, sometimes for a long time after stopping. Always tell your doctor about any past or current use, as it changes the assessment.
How do I know if it is testosterone or something else?
Only a blood test can confirm it, ideally with a check for the common mimics such as thyroid and blood count. A doctor will interpret the result together with your symptoms to reach the right answer.
Dr. Ponlawat Pitsuwan
Physician, Doctor Bangkok
Dr. Ponlawat practises at Doctor Bangkok, a private medical clinic in central Bangkok. He assesses men presenting with fatigue, low libido and mood changes, carefully separating hormone problems from the many other causes that mimic them.
Dr. Ponlawat Pitsuwan is a physician at Doctor Bangkok, a private clinic in central Bangkok. He sees expats, residents, and medical tourists for general medicine, wellness consultations, and IV therapy. His focus is straightforward, evidence-based care delivered in plain language.