Losartan does not lower testosterone. The available evidence points in the opposite direction: losartan appears to have a neutral or even mildly positive effect on testosterone levels, which sets it apart from several other blood pressure medications that can suppress the hormone. If you’re taking losartan and concerned about your testosterone, the drug itself is unlikely to be the culprit.
What the Research Shows
Most of the direct data on losartan and testosterone comes from animal studies, since large human trials specifically measuring testosterone changes on losartan haven’t been conducted. In rat models, losartan consistently either left testosterone unchanged or raised it. One study published in Frontiers in Reproductive Health found that rats treated with losartan for 60 days had testosterone levels of 2.34 ng/mL, nearly double the 1.25 ng/mL seen in untreated controls. The researchers attributed this to losartan’s ability to reduce oxidative stress and inflammation in the testes, which may help preserve the cells responsible for producing testosterone (Leydig cells).
In hypertensive rat models, losartan normalized testosterone levels that had been disrupted by high blood pressure. The mechanism involves blocking a receptor for angiotensin II, a hormone your body produces as part of blood pressure regulation. Angiotensin II doesn’t just constrict blood vessels. It also appears to interfere with reproductive hormones when levels stay elevated, as they do in uncontrolled hypertension. By blocking that signal, losartan may remove a drag on testosterone production rather than creating one.
Losartan’s FDA Label and Sexual Side Effects
The FDA-approved label for losartan does not list testosterone reduction, hypogonadism, or decreased libido among its side effects. Erectile dysfunction is listed as a reported adverse reaction in clinical trials, but this is common across nearly all blood pressure medications and doesn’t necessarily indicate a hormonal cause. Blood pressure itself, along with the underlying vascular damage that comes with hypertension, is one of the most common contributors to erectile problems in men.
This distinction matters. A drug can affect erections through blood flow changes without touching testosterone at all. The label suggests losartan occasionally does the former but provides no evidence it does the latter.
How Losartan Compares to Other Blood Pressure Drugs
Where losartan really stands out is in comparison to other medications commonly prescribed for high blood pressure. Several classes of blood pressure drugs have documented negative effects on testosterone and sexual function:
- Beta-blockers (like atenolol and propranolol) can suppress luteinizing hormone, the signal from the brain that tells the testes to produce testosterone. This leads to reduced Leydig cell activity and lower testosterone levels. One study of 156 hypertensive men found that atenolol resulted in sexual dysfunction and reduced testosterone.
- Spironolactone, an aldosterone antagonist used in heart failure, has well-documented antiandrogen effects. It can cause erectile dysfunction, breast tissue growth, and reduced libido by directly opposing testosterone’s actions.
- Thiazide diuretics like hydrochlorothiazide and chlorthalidone have been associated with worsening sexual function, though the exact mechanism isn’t fully understood.
ARBs like losartan, by contrast, have shown a different pattern. A study of 82 hypertensive men with erectile dysfunction found that losartan resulted in a marked increase in self-reported sexual satisfaction. Another randomized trial comparing the ARB valsartan (which works through the same mechanism as losartan) to the beta-blocker carvedilol in 160 previously untreated hypertensive patients found that the ARB significantly improved sexual activity while the beta-blocker did not.
Why ARBs May Help Rather Than Hurt
The potential benefit comes down to what angiotensin II does beyond raising blood pressure. Angiotensin II contributes to oxidative stress in blood vessel walls and plays a direct role in constricting the smooth muscle tissue involved in erections. By blocking this hormone’s receptor, losartan may improve blood flow to reproductive tissues while also reducing the inflammatory environment that can impair testosterone-producing cells.
In the testicular protection studies, researchers found that losartan appeared to partially preserve Leydig cell function and the process of steroidogenesis (the biochemical chain that produces testosterone) by reducing oxidative damage. This suggests the drug’s antioxidant-like properties in reproductive tissue may be just as relevant as its blood pressure effects.
What to Consider if Your Testosterone Is Low
If you’re on losartan and experiencing symptoms of low testosterone, such as fatigue, reduced sex drive, difficulty with erections, or loss of muscle mass, the medication is an unlikely explanation. More common contributors include age (testosterone declines roughly 1% per year after 30), obesity, poorly controlled blood pressure itself, sleep apnea, and chronic stress.
Uncontrolled hypertension is particularly worth considering. High blood pressure damages blood vessels throughout the body, including those supplying the testes, and elevated angiotensin II levels in untreated or undertreated hypertension can directly suppress reproductive hormones. In this context, taking losartan and effectively lowering your blood pressure may actually support healthier testosterone levels over time rather than diminish them.
If you’re currently on a beta-blocker or thiazide diuretic and noticing sexual side effects, the research suggests that switching to an ARB like losartan could be worth discussing with your prescriber. The evidence, while not from massive randomized trials, consistently favors ARBs as the blood pressure drug class least likely to interfere with testosterone and sexual health.