If you are currently being treated with any of the following medications, you
should not use vitamin A without first talking to your healthcare provider.
One study suggests that the combination of vitamin A
and antacids may be more effective than antacids alone in healing ulcers.
Birth Control Medications
Birth control medications increase
the levels of vitamin A in women. Therefore, it may not be appropriate for women
taking birth control medications to take vitamin A supplements. Again, this is
something that should be discussed with a knowledgeable healthcare provider.
Blood thinning Medications, Anticoagulants
Long-term use of
vitamin A or use of high doses may lead to an increased risk of bleeding for
those taking blood-thinning medications, particularly warfarin. People taking
this medication should notify a doctor before taking vitamin A supplements.
medications cholestyramine and colestipol (both known as bile acid
sequestrants), may reduce the body's ability to absorb vitamin A.
Another class of cholesterol-lowering medications called HMG-CoA reductase
inhibitors or statins (including atorvastatin, fluvastatin, and lovastatin,
among others) may actually increase vitamin A levels in the blood.
Test tube studies suggest that vitamin A may
enhance the action of doxorubicin, a medication used for cancer. Much more
research is needed, however, to know whether this has any practical application
This antibiotic may reduce vitamin A absorption,
especially when delivered in large doses.
Omeprazole (used for gastroesophageal reflux
disease or "heart burn") may influence the absorption and effectiveness of
beta-carotene supplements. It is not known whether this medication affects the
absorption of beta-carotene from foods.
Weight Loss Products
Orlistat, a medication used for weight
loss and olestra, a substance added to certain food products, are both intended
to bind to fat and prevent the absorption of fat and the associated calories.
Because of their effects on fat, orlistat and olestra may also prevent the
absorption of fat-soluble vitamins such as vitamin A. Given this concern and
possibility, the Food and Drug Administration (FDA) now requires that vitamin A
and other fat soluble vitamins (namely, D, E, and K) be added to food products
containing olestra. How well vitamin A from such food products is absorbed and
used by the body is not clear. In addition, physicians who prescribe orlistat
add a multivitamin with fat soluble vitamins to the regimen.
Alcohol can enhance the toxic effects of vitamin A,
presumably through its adverse effects on the liver. It is unwise to take
vitamin A if you drink regularly.