Q: What is the effect of Losartan (Cozaar) and probably other Angiotensin II receptor antagonists (ARBs) on sexual function in patients?

Answer: It improves markedly!

At least two studies have shown that ARBs improve sexual dysfuntion in hypertensive patients markedly.

In one study, 10 weeks of treatment with losartan, 88% of hypertensive males with sexual dysfunction reported improvement in at least one area of sexuality, with overall improvement in sexual satisfaction from 7.3% to 58.5%.

In another study comparing carvedilol (a Beta-Blocker), Valsartan also found to improve sexual function.

References:

1. Llisterri, JL; Lozano Vidal, JV; Aznar Vicente, J; Argaya Roca, M; Pol Bravo, C; Sanchez Zamorano, MA; Ferrario, CM (2001). "Sexual dysfunction in hypertensive patients treated with losartan". The American journal of the medical sciences 321(5): 336–41

2. Fogari, R; Zoppi, A; Poletti, L; Marasi, G; Mugellini, A; Corradi, L (2001). "Sexual activity in hypertensive men treated with valsartan or carvedilol: A crossover study". American journal of hypertension 14 (1): 27–31