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Vitamin A

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Are there any interactions with medications?



Medications for skin conditions (Retinoids)
Interaction Rating: Major Do not take this combination.

Some medications for skin conditions have vitamin A effects. Taking vitamin A pills and these medications for skin conditions could cause too much vitamin A effects and side effects.



Antibiotics (Tetracycline antibiotics)
Interaction Rating: Moderate Be cautious with this combination.
Talk with your health provider.

Vitamin A can interact with some antibiotics. Taking very large amounts of vitamin A along with some antibiotics can increase the chance of a serious side effect called intracranial hypertension. However, taking normal doses of vitamin A along with tetracyclines does not seem to cause this problem. Do not take large amounts of vitamin A if you are taking antibiotics.

Some of these antibiotics include demeclocycline (Declomycin), minocycline (Minocin), and tetracycline (Achromycin).



Medications that can harm the liver (Hepatotoxic drugs)
Interaction Rating: Moderate Be cautious with this combination.
Talk with your health provider.

Taking large amounts of vitamin A might harm the liver. Taking large amounts of vitamin A along with medications that might also harm the liver can increase the risk of liver damage. Do not take large amounts of vitamin A if you are taking a medication that can harm the liver.

Some medications that can harm the liver include acetaminophen (Tylenol and others), amiodarone (Cordarone), carbamazepine (Tegretol), isoniazid (INH), methotrexate (Rheumatrex), methyldopa (Aldomet), fluconazole (Diflucan), itraconazole (Sporanox), erythromycin (Erythrocin, Ilosone, others), phenytoin (Dilantin), lovastatin (Mevacor), pravastatin (Pravachol), simvastatin (Zocor), and many others.



Warfarin (Coumadin)
Interaction Rating: Moderate Be cautious with this combination.
Talk with your health provider.

Warfarin (Coumadin) is used to slow blood clotting. Large amounts of vitamin A can also slow blood clotting. Taking vitamin A along with warfarin (Coumadin) can increase the chances of bruising and bleeding. Be sure to have your blood checked regularly. The dose of your warfarin (Coumadin) might need to be changed.

Dosing considerations for Vitamin A.

The following doses have been studied in scientific research:

ADULTS

BY MOUTH:
  • General: Recommended Dietary Allowance (RDA) levels for adults have been established: men 14 years and older, 900 mcg/day (3000 IU); women 14 years and older, 700 mcg/day (2300 IU); pregnancy 14 to 18 years, 750 mcg/day (2500 IU); 19 years and older, 770 mcg/day (2600 IU); lactation 14 to 18 years, 1200 mcg/day (4000 IU); 19 years and older, 1300 mcg/day (4300 IU). Tolerable Upper Intake Levels (UL) for vitamin A have also been established. The UL is the highest level of intake that is likely to pose no risk of harmful effects. The ULs for vitamin A are for preformed vitamin A (retinol) and do not include provitamin A carotenoids: adolescents 14 to 18 years (including pregnancy and lactation), 2800 mcg/day (9000 IU); adults age 19 and older (including pregnancy and lactation), 3000 mcg/day (10,000 IU).

  • Vitamin A dosage is most commonly expressed in IU, but dosage in micrograms is sometimes used.
    Eating 5 servings of fruits and vegetables per day provides about 50% to 65% of the adult RDA for vitamin A.
  • For precancerous lesions in the mouth (oral leukoplakia): Weekly dose of 200,000-300,000 IU of vitamin A has been used for 6-12 months.
  • For reducing death during pregnancy: Weekly doses of 23,000 IU of vitamin E have been used before and during pregnancy.
  • For reducing night blindness during pregnancy: Weekly doses of 23,000 IU of vitamin E have been used before, during, and after pregnancy. It seems to work best if taken in combination with 35 mg of zinc daily in women who also have low levels of zinc.
  • For diarrhea after pregnancy: Weekly doses of 23,000 IU of vitamin E have been used before, during, and after pregnancy.
  • For eye disease affecting the retina (retinitis pigmentosa): Daily doses of 15,000 IU of vitamin A, sometimes along with 400 IU of vitamin E daily, has been used.
CHILDREN

BY MOUTH:
  • General: Adequate Intake (AI) levels of vitamin A for infants have been established: birth to 6 months, 400 mcg/day (1300 IU); 7 to 12 months, 500 mcg/day (1700 IU).

  • Recommended Dietary Allowance (RDA) levels for children and adults have been established: children 1 to 3 years, 300 mcg/day (1000 IU); 4 to 8 years, 400 mcg/day (1300 IU); 9 to 13 years, 600 mcg/day (2000 IU). Tolerable Upper Intake Levels (UL) for vitamin A have also been established. The UL is the highest level of intake that is likely to pose no risk of harmful effects. The ULs for vitamin A are for preformed vitamin A (retinol) and do not include provitamin A carotenoids: infants and children from birth to 3 years, 600 mcg/day (2000 IU); children 4 to 8 years, 900 mcg/day (3000 IU); 9 to 13 years, 1700 mcg/day (6000 IU); and 14 to 18 years (including pregnancy and lactation), 2800 mcg/day (9000 IU).
  • For measles: Vitamin A 100,000 to 200,000 IU orally for at least two doses has been used in children less than 2 years-old.

Therapeutic Research Faculty copyright

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