How Caffeine Affects Women Differently Than Men

Alexa Nikolai
Sep 17, 2025
3 min read

Two cups of cappuccino sit on a picnic table

Overview

Caffeine is society’s most commonly used stimulant (a substance that raises nervous system activity in the body), with 85% of US adults and 89-95% of college students reporting daily use. However, although mostly appreciated for its positive effects, caffeine can also have negative side effects and may not affect every individual in the same way.

Effects of Caffeine

Caffeine, which is usually consumed in coffee, tea, or energy drinks, is a useful tool for increasing energy and concentration. Many people come to rely on a daily cup of coffee to help them wake up or power through a long day. However, caffeine also has some negative side effects, such as an increased need to urinate, heart palpitations, anxiety or nervousness, headaches, gastrointestinal problems, or insomnia.

Although the positive effects may outweigh the negative effects for many users, it is important to understand any factors that may enhance negative effects or change how your body processes caffeine. In fact, how you respond to caffeine can depend on any number of factors, including age, level of regular caffeine consumption, training status, caffeine source, and sex.

How It Works

Caffeine is in part so effective, because it can easily cross biological membranes, thus acting on the body rapidly and thoroughly. Caffeine molecules bind to the same receptors as adenosine, a chemical in the body that increases sleepiness. When caffeine binds to these receptors, adenosine can’t, and the sympathetic nervous system is stimulated, leading to reduced fatigue, increased concentration, and enhanced athletic performance.

Sex-Based Differences

Although caffeine is effective in both males and females, use of the substance does appear to have sex-based differences. For example, while caffeine increases blood pressure and decreases heart rate in both males and females, this effect is more pronounced in males. Furthermore, female users report more negative symptoms associated with caffeine consumption, including increased urine production and more anxiety and nervousness. In general, in study groups, 54% of females report negative affects whereas only 30% of males report negative effects. On the other hand, 50% of males report experiencing positive effects after caffeine consumption, while only 20% of women report positive effects. Despite this discrepancy, in general, women report higher levels of caffeine consumption (although men report higher levels of energy drink consumption).

Female caffeine users also show a greater likelihood of using alcohol or drugs compared to female non-caffeine users (the effect is found in males, as well, but to a lesser extent). This association may be due to the fact that caffeine reduces the depressant effects of alcohol and feelings of drunkenness, factors that often encourage people to stop drinking.

Causes of Sex-Based Differences

The cause of sex-based differences in the effects of caffeine may be related to body composition. Caffeine is only distributed in lean body mass (muscles, organs, and bones, but not fat), and since females have a higher ratio of adipose (fat) tissue to lean body mass than males, the same amount of caffeine becomes more concentrated in other tissues.

Caffeine effects may also be related to hormone levels. During phases of the menstrual cycle when estradiol levels are higher (ovulation), females have been shown to have a lower response to caffeine, while experiencing more negative effects when estradiol levels are lower (early follicular phase).

Summary

Caffeine can be a useful tool on days when you need a bit of a pick-me-up, however, if you find yourself getting jittery or having a hard time falling asleep later, it may be worth cutting back. As always, pay attention to your own body and your personal reaction to coffee. If you can, also try to improve your sleep quality, and then you won't need to rely on a caffeine boost as much!