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Oral contraceptives are
medications that prevent pregnancy. They are one type of
birth control. Oral contraceptives may contain
combinations of estrogen and progestin or progestin
alone. Combinations of estrogen and progestin prevent
pregnancy by inhibiting the release of the hormones LH
and FSH from the pituitary gland in the brain. LH and
FSH play key roles in the development of the egg and
preparation of the lining of the uterus for implantation
of the embryo. Progestin also makes the uterine mucus
that surrounds the egg more difficult for sperm to
penetrate and, therefore, for fertilization to take
place. In some women, progestin inhibits ovulation
(release of the egg).
The combination Oral contraceptives are called "monophasic,"
"biphasic," or "triphasic." Monophasic Oral
contraceptives deliver the same amount of estrogen and
progestin every day. Biphasic Oral contraceptives
deliver the same amount of estrogen every day for the
first 21 days of the cycle. During the first half of the
cycle, the progestin/estrogen ratio is lower to allow
the endometrium to thicken as it normally does. During
the second half of the cycle, the progestin/estrogen
ratio is higher to allow normal shedding of the lining
of the uterus to occur. The triphasic Oral
contraceptives have constant or changing estrogen
concentrations and varying progestin concentrations
throughout the cycle. There is no evidence that bi- or
tri-phasic OCs are superior to monophasic Oral
contraceptives, or vice-versa.
Medications sold in the United States can be divided
into two categories:
Nonprescription Over the counter.
Prescription medications require a prescription to be
sold.
Nonprescription or over-the-counter medications that do
not require a directive from a doctor
Prescription medications are generally more potent than
those sold over-the-counter (OTC) and may have more
serious side effects if inappropriately used. Therefore,
these medications are only sold under a doctor’s
direction. These directions are written on a
prescription by your doctor, then double-checked,
packaged, and sold to you by a pharmacist.
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