Interactions of Drugs with Vitamin A

Chemotherapy drugs

In people undergoing chemotherapy, topical administration of vitamins A and E twice a day accelerates the healing of oral ulcers and has no side effects, but oral administration of these vitamins during chemotherapy should be avoided.

Cholestyramine

Bile-acid-degrading compounds, such as cholestyramine, reduce the digestion and absorption of fats and fat-soluble vitamins, including vitamin A.

Colchicine

Colchicine reduces the absorption of vitamin A in beta-carotene form.
In people treated with colchicine, vitamin A supplementation through multivitamins or other sources is recommended.

Colestipol

Colestipol reduces the absorption of fats and fat-soluble vitamins such as vitamins A, D, E, K, and folic acid.
Consumption of vitamin A is beneficial in people treated with Clostipol.

Corticosteroids

In people being treated with corticosteroids, more vitamin A is recommended. The amount of vitamin A required by the body in ordinary people is 25,000 units per day. In pregnant women, vitamin A intake should be limited to less than 10,000 units per day.
For people treated with corticosteroids, a daily dose of 100,000 units is recommended.

5-Fluorouracil (5-FU)

Vitamin A in the retinol form increases the antitumor activity of 5-fluorouracil, but in the beta-carotene, form decreases the activity of 5-fluorouracil.
In people treated with 5-fluorouracil, except for women who are likely to become pregnant, it is recommended to eat foods rich in retinol, especially fish liver oil.

Statins, especially lovastatin and pravastatin

Consumption of statins increases serum levels of vitamin A.
People undergoing long-term treatment with statins should avoid foods rich in vitamin A, such as carrots, kale, spinach, liver, and egg yolks.

Methotrexate

Vitamin A increases the antitumor activity of methotrexate.
Vitamin A supplements are recommended for people undergoing chemotherapy for cancer with methotrexate after consulting a doctor.

Edible paraffin (Mineral Oil)

Oral paraffin reduces the absorption of fat-soluble vitamins (A, D, K, E) and other minerals such as calcium, phosphorus, and potassium.
It is better to limit oral paraffin consumption to less than a week to prevent micronutrient deficiency in the body

Neomycin

Neomycin in oral and injectable use reduces vitamin A's absorption in the body, but topical use does not affect it.
In people who take oral neomycin for more than 2-3 days, the use of vitamin A supplements at a rate of 25,000 units per day will be beneficial.

Oral contraceptives

Taking oral contraceptives increases the serum level of vitamin A, probably due to estrogen in oral contraceptives. The above interaction and increase in serum vitamin A levels due to taking oral contraceptives are clinically significant, or no, it has not been determined yet.

Accutane (retinoic acid)

Co-administration of Accutane with supplements and foods rich in Vitamin A increases the bioavailability of Accutane and possibly Increases the incidence of Accutane poisoning.

Tetracyclines

One of the side effects of long-term use or high doses of tetracyclines is severe headaches due to increased cerebrovascular pressure. According to research, the risk of severe headaches increases with the use of tetracyclines with high doses of vitamin A.