Isotretinoin
Isotretinoin is a teratogen; there is about a 20–35% risk for congenital defects in infants exposed to the drug "in utero", and about 30–60% of children exposed to isotretinoin prenatally have been reported to show neurocognitive impairment. Because of this, there are strict controls on prescribing isotretinoin to women who may become pregnant and women who become pregnant while taking isotretinoin are strongly advised to terminate their pregnancies.
Prescription drug
As a general rule, "over-the-counter drugs" (OTC) are used to treat a condition that does not need care from a healthcare professional if have been proven to meet higher safety standards for self-medication by patients. Often, a lower strength of a drug will be approved for OTC use, but higher strengths require a prescription to be obtained; a notable case is ibuprofen, which has been widely available as an OTC pain killer since the mid-1980s, but it is available by prescription in doses up to four times the OTC dose for severe pain that is not adequately controlled by the OTC strength.