In a single-patient case report, a 53-year-old man’s erectile function recovered after his antihypertensive regimen was changed from valsartan plus amlodipine to a lower-dose combination containing olmesartan, amlodipine and hydrochlorothiazide. The patient’s International Index of Erectile Function, or IIEF-5, score rose from 12, corresponding to moderate erectile dysfunction, to 22, corresponding to normal function, within two months of the switch. Blood pressure also remained controlled. Although the temporal pattern and a Naranjo algorithm score of 7 classified the earlier erectile dysfunction as a probable adverse drug reaction, the result comes from one retrospective case and cannot establish that any single medication caused the improvement.
The patient, a married recreational cyclist and strength trainer, initially had occasional blood-pressure readings as high as 140/90 mmHg and mixed hyperlipidaemia. Lifestyle measures, including a low-sodium diet and physical activity, did not provide satisfactory control. Treatment began in December 2021 with perindopril 5 mg and atorvastatin 40 mg. Poor adherence and inadequate control led to the temporary addition of indapamide 1.5 mg. Between June and September 2025, he received fixed-dose perindopril and amlodipine combinations of 5/5 mg and then 5/10 mg, but home measurements still reached 160/97 mmHg.
On 22 October 2025, the regimen was changed to a once-daily fixed-dose tablet containing valsartan 160 mg and amlodipine 10 mg. This treatment achieved home blood-pressure readings of 120/80 to 120/85 mmHg. Within a month, however, the patient developed substantial erectile dysfunction and was considering stopping the medication despite its favorable blood-pressure effect. Because preserving sexual function was a priority for him, he asked for a treatment change. Endocrine testing found total testosterone of 14.49 nmol/L, free testosterone of 1.7% and sex hormone-binding globulin of 43.7 nmol/L, all within the reported reference ranges, making a hormonal explanation less likely.
The clinicians therefore focused on the medicines as possible contributors. Amlodipine had been part of two earlier perindopril combinations, used at 5 mg and 10 mg, without erectile dysfunction, whereas the symptom began soon after valsartan was introduced. Those observations led the treating team to suspect valsartan, even though angiotensin receptor blockers as a class are generally considered neutral or potentially beneficial for sexual function. This is a clinically important departure from the expected class profile, but it remains a hypothesis based on temporal association and prior experience in the same individual, not a demonstrated pharmacological effect.
On 4 February 2026, the patient began half a tablet daily of a fixed-dose combination containing olmesartan 40 mg, amlodipine 5 mg and hydrochlorothiazide 12.5 mg. The resulting daily doses were therefore olmesartan 20 mg, amlodipine 2.5 mg and hydrochlorothiazide 6.25 mg. At a one-month follow-up, the patient reported that his erectile symptoms had disappeared. They did not recur, and home blood-pressure measurements remained between 104/75 and 123/81 mmHg, while the clinic reading was 120/80 mmHg. The authors described this sequence as a positive dechallenge following withdrawal of valsartan and successful substitution with olmesartan without relapse.
At an April 2026 assessment, the patient retrospectively rated his erectile function under valsartan therapy as 12 on the IIEF-5, a score categorized as moderate erectile dysfunction. Two months after the switch, he rated it as 22, which falls in the normal-function category, representing a 10-point increase. The questionnaire had not been officially validated in Croatian, so an ad hoc translation was used for clinical purposes. Retrospective self-report and a nonvalidated translation introduce potential recall and measurement uncertainty even though the patient reported high satisfaction and an improvement in quality of life.
Olmesartan and valsartan share a pharmacological class but differ in receptor behavior and several other properties. Olmesartan medoxomil is a prodrug converted during absorption to active olmesartan; the source reports that this modification raises bioavailability from 6% to 28.6% and that olmesartan has little inhibitory effect on cytochrome P450 enzymes, giving it a low potential for drug interactions. The active drug binds with high affinity to angiotensin II type 1, or AT1, receptors and has a slow dissociation rate. Crystallographic evidence described in the report indicates that olmesartan uses a double-chain binding arrangement involving the amino-acid residues Tyr113 and His256, whereas valsartan binds primarily to Lys199 and dissociates more rapidly.
Those molecular differences provide a possible explanation for why two drugs in the same class did not have the same observed effect in this patient, although the case cannot prove that mechanism. The report describes olmesartan as an inverse agonist that stabilizes AT1 receptors in an inactive state, potentially producing more sustained blockade of angiotensin II. It also cites evidence that olmesartan can reduce oxidative stress and microinflammation, influence resistance-vessel remodeling and suppress angiotensin-II-induced intracellular radical production. These vascular actions are relevant because endothelial dysfunction can impair the vasodilation needed for erection, but most of the supporting evidence summarized in the case report comes from broader pharmacological research and animal models rather than a controlled human comparison of valsartan and olmesartan for erectile function.
Experimental work in hypertensive animals provides the most direct evidence cited for a sexual-function effect. In those models, olmesartan reduced malondialdehyde concentrations, used as a marker of oxidative stress, in the corpus cavernosum and increased messenger RNA levels for endothelial and neuronal nitric oxide synthase in penile tissue. The authors propose that greater nitric-oxide availability could improve cavernosal vascular function and potentially counteract the vasoconstrictor effects of a thiazide diuretic. This mechanism remains a plausible hypothesis: the experiment involved animals, and the reported human outcome came from a single person whose treatment changed in several ways at the same time.
Three simultaneous medication changes prevent the improvement from being attributed uniquely to olmesartan: valsartan was replaced, amlodipine was reduced from 10 mg to 2.5 mg, and hydrochlorothiazide was introduced at 6.25 mg. The very low thiazide dose is also relevant because diuretics have historically been associated with erectile dysfunction and treatment discontinuation, although the cited studies used substantially larger doses. Adding a diuretic while function improved does not support the idea that hydrochlorothiazide caused the earlier problem, but it does further complicate identification of the active causal ingredient. The case therefore supports a clinical question—can individual responses differ within the angiotensin receptor blocker class?—rather than a general treatment claim. Larger controlled trials would be needed to determine whether the apparent difference between valsartan and olmesartan is reproducible and whether either drug directly affects erectile function in broader patient populations.
Subject of Research: A case report of improved erectile function after switching from valsartan to an olmesartan-based antihypertensive regimen in one 53-year-old man.
Article Title: Improvement of Erectile Function After Switching From Valsartan to Olmesartan Within a Fixed‐Dose Antihypertensive Combination: A Case Report
Article References: Ćurković, M., & Ćurković, N. (2026). Improvement of Erectile Function After Switching From Valsartan to Olmesartan Within a Fixed‐Dose Antihypertensive Combination: A Case Report. Clinical Case Reports, 14(10), Article e73718. https://doi.org/10.1002/ccr3.73718
Image Credits: AI Generated
DOI: 10.1002/ccr3.73718
Keywords: erectile dysfunction, antihypertensive therapy, olmesartan, valsartan, angiotensin receptor blockers, amlodipine, hydrochlorothiazide, case report, vascular function, Improvement, Erectile, Function
News Source: Ophelia Keating. (October 20, 2026). Erectile Function Improved After Antihypertensive Switch in One Patient. Scienmag.
