oral contraceptives
6 interactions related to oral contraceptives
oral contraceptives + vitamin b6
Combined (estrogen-containing) oral contraceptives modestly lower the active form of vitamin B6, pyridoxal 5'-phosphate, by speeding up tryptophan metabolism. Long-term pill users tend to show lower B6 status markers than non-users. This is a depletion of a status marker rather than a clinical safety problem, and it does not affect how well the pill works.
oral contraceptives + st. john's wort
St. John's Wort induces CYP3A4 and P-glycoprotein, increasing the clearance of contraceptive hormones and reducing the effectiveness of hormonal contraceptives.
oral contraceptives + magnesium
Observational studies dating back to the 1970s have found that women taking combined oral contraceptives tend to have somewhat lower serum magnesium levels than non-users, likely through estrogen-related shifts in how the body distributes and excretes magnesium. This is a nutritional observation, not a contraceptive-failure risk. Magnesium does not reduce the pill's effectiveness, and links between low magnesium and pill side effects or clotting risk remain theoretical rather than proven.
smoking + oral contraceptives
Combining cigarette smoking with combined (estrogen-containing) oral contraceptives raises the risk of heart attack, stroke, and blood clots more than either exposure alone, especially after age 35 and with heavier smoking.
oral contraceptives + folate
Combined oral contraceptive use is associated with modestly lower plasma and red blood cell folate levels, likely through increased turnover and urinary excretion. Because fertility can return quickly after stopping the pill, lower folate stores at that moment can matter for the neural tube risk of an early pregnancy.
caffeine + oral contraceptives
Ethinyl estradiol in combined oral contraceptives inhibits CYP1A2, the liver enzyme that clears caffeine. This slows caffeine's breakdown and prolongs its half-life, so the same cup of coffee can leave more caffeine circulating for longer and intensify jitteriness, insomnia and palpitations.