Intravaginal ejaculation latency time (IELT) is defined as the time between the start of vaginal intromission and the start of intravaginal ejaculation.[1] IELT can help evaluate sexual effects of medications such as selective serotonin reuptake inhibitors (SSRIs). IELT is one factor used to diagnose and treat conditions such as premature ejaculation.[1] Sexual performance and satisfaction depend on many factors.
Researchers have made conflicting discoveries about IELT. In a multinational study,[1] the authors studied 491 men in the Netherlands, Spain, Turkey, UK, and US. The men were in stable heterosexual relationships. Over a four-week period, couples recorded IELT data using a stopwatch and noted condom use. Median IELT was independent of condom use. Median IELT decreased with age (18-30: 6.5 minutes, 31-50: 5.4 minutes, 51+: 4.3 minutes). Median IELT for all participants was 5.4 minutes. Median IELT varied significantly by individual with 14% of men under 3:20 and 26% of men over 10:00. Potential problems include total sample size, small sample size per country, too few observations for each participant, and psychological effects of using a stopwatch.
In an early study, Alfred Kinsey found that 75% of men climaxed within 2 minutes of penetration at least half of the time.[2] In their book Human Sexual Response, Masters and Johnson published a variety of findings on sexual response and satisfaction based on direct observation and medical exams. Sexual satisfaction is independent of how long intercourse lasts.[3] A man's response time varies with a woman's menstrual cycle; shorter IELTs occur nearest to ovulation.[4] Both partners' sexual experience also affects latency time.
Numerous chemical substances influence IELT. Some increase IELT by depressing the central nervous system. Alcohol and opiates (e.g.: heroine, oxycodone, morphine) fit in this group. Other substances act in different ways. Tetrahydrocannabinol (THC]), present in marijuana, inhibits sexual arousal and orgasm. Selective serotonin reuptake inhibitors (SSRIs) delay ejaculation by blocking a physiological process connected to the male point of no return (ejaculatory inevitability). For that reason, SSRIs can be prescribed to treat premature ejaculation.