The purpose of this qualitative study was to explore the sexual high-risk behaviors of methamphetamine user males. The study showed that methamphetamine use could increase sexual high-risk behaviors. These results are consistent with the results of studies which have done in other countries (
8,
10,
11). In Iran, an opioid substitution treatment program could control the intravenous use of illicit heroin and HIV transmission. However, HIV transmission through sexual high-risk behaviors in methamphetamine users and their partners remained the main challenge (
12). Amphetamines, not only through their intravenous use, but also through increasing sexual high-risk behaviors, increase the risk of HIV transmission (
2). The results of this study showed methamphetamine could cause sexually high- risk behaviors in heterosexuals and this is consistent with other few studies (
10). Sexual relationships with the unknown HIV status partners and anal intercourse could increase the risk of HIV transmission significantly (
10). In addition, in HIV-positive people, there is higher association between methamphetamine use and sexual high-risk behaviors that could increase the risk of HIV transmission (
13). Some of the participants described their sexual behaviors' essence was compulsive and some of them use the term “sexual addiction” to describe their behaviors. Other researchers reported sexual compulsion as well (
14). It seems sexual addiction is not simply a subcultural behavior pattern, and it would be a biological effect of methamphetamine use (
15). In this study both physicians and methamphetamine users believed that with a few months of abstinence, the methamphetamine-related sexual behaviors would change to normal, the intensity of sexual desire would decrease, and the sexual profile would improve. The negative effects of methamphetamine on decision-making (
16), and control of sexual behavior (
17), may be other reasons for changes in sexual behavior. Therefore, the methamphetamine users are unable to inhibit the behaviors that are not socially and morally desirable. In the present study, the methamphetamine users often were self-medicated with sildenafil. According to studies, taking medications like sildenafil is more common in methamphetamine users who report engaging in sexual marathon (
5). The people who take the combination of methamphetamine and Viagra have more sexual partners (
18), engage in sexual high- risk behaviors (
19), and this combination is strongly associated with a much higher prevalence rate of HIV (
20). In addition, according to some studies methamphetamine could affect the sexual orientation. There is an association between methamphetamine use and attraction to the same sex relationships in men (
5). In the present study, most of the users denied any changes in their sexual orientation. However, it could be due to the small sample size, and the social stigma of homosexuality in Iran. There are few studies on sexual marathon (a prolonged sexual activity that last hours in a session) in methamphetamine users. The main mechanisms contributing to this phenomenon include increased sexual drive and behavioral disinhibition (
2). In Semple et al. study, more than 80% of MSM users reported engaging in marathon sex while they were high on methamphetamine and users who took sildenafil were six times more likely to have participated in marathon sex (
5). Condom use is one of the most common harm reduction strategies and its use is highly dependent on the attitudes of people towards it (
21). Illicit drug use is associated with an increase in high-risk behaviors and impaired judgment. Therefore, methamphetamine users have a lower tendency to use condom (
13). Another important point is that methamphetamine users may experience impotence, in spite of preserved or even increased sexual desire. Their inability to use condom as a result of impaired erection, could result in a risky sexual behavior. The results of the present study demonstrate methamphetamine-related sexual promiscuity. This is consistent with other studies such as the study of Liu et al. that showed having multiple sexual partners is more common in heterosexual methamphetamine users (
22). Also, the sex workers who use methamphetamine have more partners and have more relationships with methamphetamine users (
23). In the present study, methamphetamine users tended to have group sex and sexual activity in open spaces. These changes are late consequences of methamphetamine use and would alleviate during abstinence. According to the qualitative study performed by Reback et al. the number of sexual relationships with unknown partners decreased during the abstinence phase and the persons demonstrated stronger commitment to their partner (
24). Because of the type (qualitative) and limitations of this study, we cannot determine exactly the pattern of sexual high-risk behaviors among the participants; so, we suggest future quantitative studies about this issue.