What Causes Low Testosterone? 8 Common Reasons in Men

Medically reviewed by Meg LaFerriere, APRN · Ageless KC, Lee’s Summit, MO

Low testosterone is a result, not a root cause. Knowing why your levels dropped matters as much as the number itself.

What are the most common causes of low T?

Doctors group low testosterone into two types. Primary low T starts in the testes. Secondary low T starts in the brain, where the pituitary gland stops sending a strong enough signal. Here are eight common contributors:

1. Aging: a slow, gradual decline in many men.
2. Obesity: excess body fat lowers testosterone and the signals that drive it.
3. Type 2 diabetes: strongly linked to low testosterone.
4. Obstructive sleep apnea: disrupted sleep and low oxygen can suppress levels.
5. Opioid medications: a well-known cause of secondary low T.
6. Glucocorticoids and anabolic steroids: including past steroid use.
7. Pituitary conditions: such as a prolactin-producing tumor.
8. Testicular issues: injury, infection like mumps, chemotherapy, radiation or genetic conditions such as Klinefelter syndrome.

How does body weight lower testosterone?

Fat tissue contains an enzyme called aromatase, which converts some testosterone into estradiol. More body fat, especially around the abdomen, is also linked to insulin resistance and lower SHBG. Together, these changes can lower total testosterone and weaken the pituitary’s signal.

The relationship goes both ways. Low testosterone can make it easier to gain fat and harder to keep muscle. Studies show that meaningful weight loss often raises testosterone in men with obesity.

Can sleep apnea and poor sleep cause low T?

Yes. Much of your daily testosterone release happens during sleep. Obstructive sleep apnea, which causes repeated breathing pauses at night, is linked to lower levels. Chronic short sleep can lower testosterone too.

Loud snoring, gasping at night, morning headaches and daytime sleepiness are reasons to ask about a sleep study. This also matters for treatment, since testosterone therapy can worsen untreated sleep apnea.

Which medications can lower testosterone?

Long-term opioid pain medications are one of the clearest causes. Others include high-dose or long-term glucocorticoids (like prednisone), some hormone treatments for prostate cancer, and past anabolic steroid use, which can shut down natural production for months or longer.

Never stop a prescribed medication on your own. Bring a full list to your visit so your practitioner can review it with you and your prescribing clinician.

Supplements count too. Some products sold online as “testosterone boosters” or for muscle building have been found to contain hidden hormones or steroids. These can suppress your own production and make your labs harder to interpret, so mention anything you’ve taken in the past year.

Curious about the cost of a workup? Consultation and lab prices are on our pricing page.

How do clinicians find the cause?

After two early-morning tests confirm low total testosterone, the AUA recommends checking LH. A high LH points toward the testes. A low or normal LH points toward the pituitary or outside factors, and prolactin is usually checked next.

Lab pattern	Likely type	Possible next step
Low T, high LH	Primary (testicular)	Review history, possible genetic testing
Low T, low/normal LH	Secondary (pituitary or functional)	Check prolactin, review weight, sleep, medications
Low T, high prolactin	Possible pituitary cause	Repeat test, imaging, endocrinology referral

Our men’s hormone program in Lee’s Summit starts with this kind of careful workup. If something needs a specialist, you’ll be referred.

Frequently asked questions

Can stress cause low testosterone?

Severe physical stress, like serious illness or intense overtraining with too little food, can lower testosterone. Everyday stress may contribute indirectly through poor sleep, weight gain and alcohol use.

Does alcohol lower testosterone?

Heavy drinking is linked to lower testosterone and can damage the testes and liver over time. Moderate or occasional drinking has less effect, but cutting back is one of the simpler changes you can make.

Can low testosterone be cured?

It depends on the cause. Low T from obesity, sleep apnea or medications may improve when those are addressed. Primary testicular causes usually don’t reverse, and treatment focuses on managing symptoms safely.

Sources: American Urological Association 2018 Testosterone Deficiency Guideline; Endocrine Society Clinical Practice Guideline (2018); Mayo Clinic; Cleveland Clinic; NIH/MedlinePlus

This article is for general education and isn’t medical advice. Treatments aren’t right for everyone, and results vary. Our practitioner reviews your health history before any treatment.