The probability of side effects with ovral, norinyl 1/50 and norlestrin.

This report provides specific information on the prevalence rates of the most common side effects during the first 3 cycles of use of 3 combination oral contraceptives (OCs) containing 50 mcg estrogen. The probabilities of a symptom occurring for the first time, or persisting once present, during the initial cycles of OC use are given for each of the 3 combined OCs.