Grapefruit adversely
reacts with many prescription drugs. It can elevate the level of
medication in your blood, increasing your risk for serious side effects.
However, Synthroid, a brand-name thyroid replacement medication, does
not interact dangerously with grapefruit, based on evidence available
as of 2011. But new medical and drug interaction information could
change this assessment. If you take Synthroid or any other medication,
ask your doctor or pharmacist about updates on their interactions with
grapefruit.
No Known Interaction
MedlinePlus,
a service of the National Institutes of Health, does not list
grapefruit among its interaction warnings for Synthroid. Additionally,
the United States Food and Drug Administration's most currently
available label for Synthroid, approved on July 14, 2008, does not list
grapefruit as a substance to avoid while taking Synthroid. According to
the People's Pharmacy, however, the majority of drugs remain untested
for possible interactions with grapefruit.
CYP34A Enzyme Inhibition
Grapefruit
reacts adversely with many medications because it inhibits your CYP34A
enzyme from metabolizing drugs. Some drugs and some people are more
sensitive to grapefruit's effect on this enzyme. If grapefruit slows the
metabolism of a drug you take, you may end up with an excess of the
medication in your system -- an overdose. An elevated dose of medication
may increase the effectiveness of a medication and your risk for side
effects.
Synthroid Uses and Side Effects
Synthroid
treats a condition called hypothyroidism. Hypothyroidism develops when
your body does not naturally produce enough of the thyroid hormone.
Doctors may also prescribe Synthroid to treat goiter, a condition caused
by an enlarged thyroid gland. Side effects of Synthroid include
vomiting, nausea, tremors, weight loss,
insomnia and hair loss. Theoretically, combining grapefruit with
Synthroid could increase your risk for these symptoms. However, no
evidence available as of 2011 suggests that it will.
Known Drug Interactions
Drugs
known to interact adversely with grapefruit include oral
contraceptives, statins, calcium channel blockers, antidepressants,
anti-anxiety medications and immunosuppressants. This is simply a
partial list. For a full list of known drug interactions
with grapefruit, consult a medical professional. Serious side effects
include blood clots, gangrene, strokes and heart attacks .A single glass
of grapefruit may slow your body's metabolism of a drug by 47 percent,
according to the Harvard Medical School Family Health Guide.
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