Although it is a powerful antifungal medication, Diflucan can cause severe birth defects, including permanent and fatal abnormalities.  It is typically taken orally and administered over several days.  Most of the problems associated with the drug’s primary ingredient, fluconazole, are seen in patients who are taking large dosages of the medication.  Several case reports confirm this, and the relatively large amount of high-quality data was enough for the Federal Drug Administration (FDA) to define fluconazole into Pregnancy Category D and release a drug safety communication to the public.


Fluconazole, like many antifungal medications, prevents the fungus from activating certain biological processes required for survival.  Among these is preventing the creation of ergosterol from the steroid lanosterol.  Ergosterol is an essential building block in the fungi’s cell membrane.  It is typically used to treat vaginal, mouth or throat infections, although it is also effective in treating meningitis caused by a certain species of fungus.  However, fluconazole has a tendency to create resistance in some species, which may urge the doctor to prescribe a higher dosage.  This can be problematic in pregnant women.

Medications in the FDA’s Pregnancy Category D have shown positive evidence that they can cause adverse reactions in developing fetuses.  For most drugs in category D, the risks outweigh the benefits of treatment, but the doctor may still prescribe the drug in rare cases.  Fluconazole is particularly dangerous in high doses, which concerns patients taking between 400 and 800 milligrams a day.  At least four studies have confirmed the elevated risk associated with high doses of Diflucan and severe birth defects.  These studies reviewed patient data of women who took the medication while pregnant and had a child with a developmental abnormality.

Fluconazole contains teratological compounds which can cause profound problems in the fetus during development.  The complication most associated with fluconazole is Tetralogy of Fallot.  This deformity results in profound abnormalities in the heart.  This may include narrowing of valves in the heart, a hole between ventricles in the heart, or a malformed aorta valve.  Teratology of Fallot causes a number of symptoms and usually results in lifelong heart murmurs and extreme sensitivity to other fatal heart conditions.

Other Diflucan related birth defects include brachycephaly (abnormal skull fusing, resulting in deformed growth of the head), cleft palate (abnormal formation of mouth or lip tissue), arthrogryposis (chronic joint and muscle problems), facial abnormalities, problematic bone growth (like thin ribs or deformed thigh bone), and various heart conditions.  While most of these complications are not life threatening, they can severely impact the child’s quality of life and growth if not treated.  Unfortunately, correcting abnormalities like these is difficult and expensive.  For this reason, many families have filed a lawsuit against Pfizer because the company did not perform adequate safety research of fluconazole.  Any woman who has had a child with a developmental abnormality after taking fluconazole while pregnant should consider speaking to a drug injury lawyer.  The compensation a family may receive for their case can help pay medical bills for treatment and improve the long term prognosis for the child.