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Other drug names: | A-Am An-Az B C-Ch Ci-Cz D-Dh Di-Dz E F G H I-J K-L M-Mh Mi-Mz N-Nh Ni-Nz O P-Pl Pm-Pz Q-R S-Sn So-Sz T-To Tp-Tz U-V W-Z 0-9 |
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In the U.S.—
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In Canada—
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Another commonly used name is retinol.
Vitamins (VYE-ta-mins) are compounds that you must have for growth and health. They are needed in small amounts only and are usually available in the foods that you eat. Vitamin A is needed for night vision and for growth of skin, bones, and male and female reproductive organs. In pregnant women vitamin A is necessary for the growth of a healthy fetus.
Lack of vitamin A may lead to a rare condition called night blindness (problems seeing in the dark), as well as dry eyes, eye infections, skin problems, and slowed growth. Your health care professional may treat these problems by prescribing vitamin A for you.
Some conditions may increase your need for vitamin A. These include:
In addition, infants receiving unfortified formula may need vitamin A supplements.
Vitamin A absorption will be decreased in any condition in which fat is poorly absorbed.
Increased need for vitamin A should be determined by your health care professional.
Claims that vitamin A is effective for treatment of conditions such as acne or lung diseases, or for treatment of eye problems, wounds, or dry or wrinkled skin not caused by lack of vitamin A have not been proven. Although vitamin A is being used to prevent certain types of cancer, some experts feel there is not enough information to show that this is effective, particularly in well-nourished individuals.
Injectable vitamin A is given by or under the supervision of a health care professional. Other forms of vitamin A are available without a prescription.
Vitamin A is available in the following dosage forms:
Vitamins alone will not take the place of a good diet and will not provide energy. Your body needs other substances found in food, such as protein, minerals, carbohydrates, and fat. Vitamins themselves often cannot work without the presence of other foods. For example, small amounts of fat are needed so that vitamin A can be absorbed into the body.
The daily amount of vitamin A needed is defined in several different ways.
Note: |
Based on 1980 U.S. Recommended Dietary Allowances (RDAs) for vitamin A in the diet that is a combination of retinol and beta-carotene. |
Note: |
Based on 1980 U.S. Recommended Dietary Allowances (RDAs) for vitamin A in the diet that is a combination of retinol and beta-carotene. |
In the past, the RDA and RNI for vitamin A have been expressed in Units. This term Units has been replaced by retinol equivalents (RE) or micrograms (mcg) of retinol, with 1 RE equal to 1 mcg of retinol. This was done to better describe the two forms of vitamin A, retinol and beta-carotene. One RE of vitamin A is equal to 3.33 Units of retinol and 10 Units of beta-carotene. Some products available have not changed their labels and continue to be labeled in Units.
If you are taking this dietary supplement without a prescription, carefully read and follow any precautions on the label. For vitamin A, the following should be considered:
Allergies—Tell your health care professional if you have ever had any unusual or allergic reaction to vitamin A. Also tell your health care professional if you are allergic to any other substances, such as foods, preservatives, or dyes.
Pregnancy—It is especially important that you are receiving enough vitamins when you become pregnant and that you continue to receive the right amount of vitamins throughout your pregnancy. The healthy growth and development of the fetus depend on a steady supply of nutrients from the mother.
However, taking too much vitamin A (more than 1800 RE [6000 Units]) during pregnancy can also cause harmful effects such as birth defects or slow or reduced growth in the child.
Breast-feeding—It is especially important that you receive the right amounts of vitamins so that your baby will also get the vitamins needed to grow properly. However, taking large amounts of a dietary supplement while breast-feeding may be harmful to the mother and/or baby and should be avoided.
Children—Problems in children have not been reported with intake of normal daily recommended amounts. However, side effects from high doses and/or prolonged use of vitamin A are more likely to occur in young children than adults.
Older adults—Problems in older adults have not been reported with intake of normal daily recommended amounts. However, some studies have shown that the elderly may be at risk of high blood levels of vitamin A with long-term use.
Dental
High doses and/or prolonged use of vitamin A may cause bleeding from the gums; dry or sore mouth; or drying, cracking, or peeling of the lips.
Other medicines—Medicines or other dietary supplements
Although certain medicines or dietary supplements should not be used together at all, in other cases they may be used together even if an interaction might occur. In these cases, your health care professional may want to change the dose, or other precautions may be necessary. When you are taking vitamin A, it is especially important that your health care professional know if you are taking any of the following:
Dosing—
The amount of vitamin A needed to meet normal daily recommended intakes will be different for different individuals. The following information includes only the average amounts of vitamin A. The combination of retinol and beta-carotene in the diet is based on 1980 U.S. Recommended Dietary Allowances (RDAs).
Note: |
Vitamin A is used in measles and xerophthalmia only when vitamin A deficiency is a problem as determined by your health care professional. Vitamin A deficiency occurs in malnutrition or in certain disease states. |
Missed dose—
If you miss taking a vitamin for one or more days there is no cause for concern, since it takes some time for your body to become seriously low in vitamins. However, if your health care professional has recommended that you take this vitamin, try to remember to take it as directed every day.
For individuals taking the oral liquid form of vitamin A:
Storage—
To store this dietary supplement:
Vitamin A is stored in the body; therefore, when you take more than the body needs, it will build up in the body. This may lead to poisoning and even death. Problems are more likely to occur in:
Remember that the total amount of vitamin A you get every day includes what you get from foods that you eat and what you take as a supplement.
Along with its needed effects, a dietary supplement may cause some unwanted effects. Vitamin A does not usually cause any side effects at normal recommended doses.
However, taking large amounts of vitamin A over a period of time may cause some unwanted effects that can be serious. Check with your health care professional immediately if any of the following side effects occur, since they may be signs of sudden overdose:
Check with your health care professional as soon as possible if any of the following side effects occur, since they may also be signs of gradual overdose:
Other side effects not listed above may also occur in some individuals. If you notice any other effects, check with your health care professional.
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Page last updated: 22 October 2004 |