Health Guide
Drug Guide

Niacin (Oral route, parenteral route)



Uses of This Medicine:

Vitamins 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. Niacin and niacinamide are necessary for many normal functions of the body, including normal tissue metabolism. They may have other effects as well.

Lack of niacin may lead to a condition called pellagra. Pellagra causes diarrhea, stomach problems, skin problems, sores in the mouth, anemia (weak blood), and mental problems. Your health care professional may treat this by prescribing niacin for you.

Some conditions may increase your need for niacin. These include:

Increased need for niacin should be determined by your health care professional.

Claims that niacin is effective for treatment of acne, alcoholism, unwanted effects of drug abuse, leprosy, motion sickness, muscle problems, poor circulation, and mental problems, and for prevention of heart attacks, have not been proven. Many of these treatments involve large and expensive amounts of vitamins.

Injectable niacin and niacinamide are given by or under the supervision of a health care professional. Other forms of niacin and niacinamide are available without a prescription.

For good health, it is important that you eat a balanced and varied diet. Follow carefully any diet program your health care professional may recommend. For your specific dietary vitamin and/or mineral needs, ask your health care professional for a list of appropriate foods. If you think that you are not getting enough vitamins and/or minerals in your diet, you may choose to take a dietary supplement.

Niacin is found in meats, eggs, and milk and dairy products. Little niacin is lost from foods during ordinary cooking.

Vitamins alone will not take the place of a good diet and will not provide energy. Your body also needs other substances found in food such as protein, minerals, carbohydrates, and fat. Vitamins themselves often cannot work without the presence of other foods.

The daily amount of niacin needed is defined in several different ways.

Normal daily recommended intakes in milligrams (mg) for niacin are generally defined as follows:

Infants birth to 3 years of age5–94–9
Children 4 to 6 years of age1213
Children 7 to 10 years of age1314–18
Adolescent and adult males15–2014–23
Adolescent and adult females13–1514–16
Pregnant females1714–16
Breast-feeding females2014–16

Before Using This Medicine:

If you are taking a dietary supplement without a prescription, carefully read and follow any precautions on the label. For these supplements, the following should be considered:


Tell your doctor if you have ever had any unusual or allergic reaction to medicines in this group or any other medicines. Also tell your health care professional if you have any other types of allergies, such as to foods dyes, preservatives, or animals. For non-prescription products, read the label or package ingredients carefully.


Problems in children have not been reported with intake of normal daily recommended amounts.

Older adults

Problems in older adults have not been reported with intake of normal daily recommended amounts.


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 large amounts of a dietary supplement in pregnancy may be harmful to the mother and/or fetus and should be avoided.


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.

Other medicines

Although certain medicines should not be used together at all, in other cases two different medicines may be used together even if an interaction might occur. In these cases, your doctor may want to change the dose, or other precautions may be necessary. Tell your healthcare professional if you are taking any other prescription or nonprescription (over-the-counter [OTC]) medicine.

Other interactions

Certain medicines should not be used at or around the time of eating food or eating certain types of food since interactions may occur. Using alcohol or tobacco with certain medicines may also cause interactions to occur. Discuss with your healthcare professional the use of your medicine with food, alcohol, or tobacco.

Other medical problems

The presence of other medical problems may affect the use of dietary supplements in this class. Make sure you tell your doctor if you have any other medical problems, especially:

Proper Use of This Medicine:

If this dietary supplement upsets your stomach, it may be taken with meals or milk. If stomach upset (nausea or diarrhea) continues, check with your health care professional.

For individuals taking the extended-release capsule form of this dietary supplement:

For individuals taking the extended-release tablet form of this dietary supplement:


The dose medicines in this class will be different for different patients. Follow your doctor's orders or the directions on the label. The following information includes only the average doses of these medicines. If your dose is different, do not change it unless your doctor tells you to do so.

The amount of medicine that you take depends on the strength of the medicine. Also, the number of doses you take each day, the time allowed between doses, and the length of time you take the medicine depend on the medical problem for which you are using the medicine.

Missed dose

If you miss a dose of this medicine, take it as soon as possible. However, if it is almost time for your next dose, skip the missed dose and go back to your regular dosing schedule. Do not double doses.

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.


Keep out of the reach of children.

Store the medicine in a closed container at room temperature, away from heat, moisture, and direct light. Keep from freezing.

Do not keep outdated medicine or medicine no longer needed.

Precautions While Using This Medicine:

This dietary supplement may cause you to feel dizzy or faint, especially when you get up from a lying or sitting position. Getting up slowly may help. This effect should lessen after a week or two as your body gets used to the dietary supplement. However, if the problem continues or gets worse, check with your health care professional.

Side Effects of This Medicine:

Along with its needed effects, a medicine may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

Check with your doctor immediately if any of the following side effects occur:

With injection only
Skin rash or itching
With prolonged use of extended-release niacin
Darkening of urine
light gray-colored stools
loss of appetite
severe stomach pain
yellow eyes or skin

Some side effects may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects. Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:

Less common
(with niacin only)
Feeling of warmth
flushing or redness of skin, especially on face and neck
With high doses
dizziness or faintness
dryness of skin
frequent urination
itching of skin
joint pain
muscle aching or cramping
nausea or vomiting
side, lower back, or stomach pain
swelling of feet or lower legs
unusual thirst
unusual tiredness or weakness
unusually fast, slow, or irregular heartbeat

Other side effects not listed may also occur in some patients. If you notice any other effects, check with your healthcare professional.

Call your doctor for medical advice about side effects. You may report side effects to the FDA at 1-800-FDA-1088.

Last Updated: 6/12/2013

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Thomson & A.D.A.M