Caffeine, usually from coffee, tea, caffeinated soda or cacao, could be considered one the world’s “favorite drugs” (1,2). On average, a person consumes approximately 165 milligrams of caffeine, or approximately 1–2 cups of coffee or caffeinated tea, per day (1,2).
What is the biological effect of caffeine?
Caffeine functions as a stimulant in the body, primarily interrupting the function of the neurotransmitter adenosine(3). When caffeine is absent, adenosine binds to its receptors (in the brain and body), which can make you feel tired or less focused (3). Caffeine competes with adenosine for those same receptors, which leads to stimulation, particularly in the brain and spinal cord (3). This stimulation can result in a feeling of increased energy, though some people may also experience jitteriness, headaches, nervousness and sleep disturbances (3).
Caffeine and PMS
The American College of Obstetricians and Gynecologists (ACOG) currently recommends that people who experience premenstrual syndrome (PMS) avoid caffeine consumption (4), as evidence exists that women with PMS tend to consume more caffeine than those who do not (5–9). On the other hand, there are studies that suggest that there is no association (10–13).
Caffeine intake and PMS may be associated anecdotally and statistically, as fatigue and depression are common symptoms of PMS (14). In general, women in the luteal phase (the second half of the cycle, after ovulation) are found to have slower response time in cognitive tasks (15), and women with PMS performed worse on psychomotor tasks during their luteal phases as compared to during their follicular phases (the first half of their cycle, before and up to ovulation) (16). These studies suggest that as women approach menstruation, they may experience fatigue and mental exhaustion, especially if they suffer from PMS.
People who experience fatigue may try to treat this symptom with increased caffeine consumption, leading to the reported association. Alternatively, women who consume high amounts of caffeine may also practice other behaviors, such as smoking, that are also associated with PMS (17), leading to a false association between caffeine intake and PMS.
It’s difficult to say whether caffeine intake can actually cause PMS, because it’s hard to prove that exposure to caffeine can lead to the outcome of PMS. Only one study has examined caffeine intake before diagnosis of PMS, and no association was found (13).
Fatigue and the follicular phase
If you tend to feel fatigue during your follicular phase (the first half of the cycle), a small increase in caffeine intake may be a suitable option for you, as long as you don’t experience any negative side effects. Alternatively, you could try addressing symptoms by increasing your intake of iron-rich foods. Premenopausal women have been shown to benefit from iron supplementation, particularly during menstruation (18–20). Foods rich in iron include red meat, chicken, tuna, leafy greens, tofu, lentils and some dried fruits (21).
Extreme exhaustion, such as an inability to get out of bed in the morning or to stay awake during the day, is not normal and may be a sign of something more serious such as anemia (22) or depression (23). If you regularly experience extreme exhaustion, especially if coupled by heavy menstrual bleeding or other irregular menstrual symptoms, it may be good to seek the advice of a medical professional.
Clue can help you track symptoms of fatigue and depressed mood under the Energy, Motivation and Mental categories. If you’re curious about caffeine’s effect on your cycle, try adding a tag, such as “high caffeine intake” or “nauseous from caffeine,” in the Tags section.