Medical Editor: John P. Cunha, DO, FACOEP Last updated on RxList: 2/1/2022

Drug Summary

What Is B12?

B12 [vitamin b12 (liver-stomach concentrate with intrinsic factor)] is an anti-anemia preparation used to treat anemias that respond to oral hematinics, including pernicious anemia and other megaloblastic anemia and also iron-deficiency anemia. B12 is available in generic form.

What Are Side Effects of B12?

Side effects of B12 are uncommon but may include:

  • diarrhea
  • constipation
  • skin rash suggesting allergy

Dosage for B12

The dose of B12 is one capsule twice a day.

What Drugs, Substances, or Supplements Interact with B12?

B12 may interact with other drugs or supplements. Tell your doctor all medications and supplements you use.

B12 During Pregnancy or Breastfeeding

During pregnancy, B12 should be used only if prescribed. It is unknown if this drug passes into breast milk. Consult your doctor before breastfeeding.

Additional Information

Our B12 [vitamin b12 (liver-stomach concentrate with intrinsic factor)] Side Effects Drug Center provides a comprehensive view of available drug information on the potential side effects when taking this medication.

Drug Description


A Highly Potent Oral Antianemia Preparation

Each capsule contains:

Special Liver-Stomach Concentrate (containing Intrinsic Factor) 240mg
Vitamin B 12 (activity equivalent) 15mcg
Iron, Elemental (as Ferrous Fumarate) 110mg
Ascorbic Acid (Vitamin C) 75 mg
Folic Acid 0.5 mg

with other factors of Vitamin B Complex present in the Liver-Stomach Concentrate.

Inactive Ingredients: D&C Red #28, FD&C Blue #1, FD&C Red #40, gelatin, magnesium stearate, povidone, silicon dioxide, sodium lauryl sulfate, starch and titanium dioxide.

Indications & Dosage


Hematinic concentrate with intrinsic factor is a multifactor preparation effective in the treatment of anemias that respond to oral hematinics, including pernicious anemia and other megaloblastic anemias and also iron-deficiency anemia. Therapeutic quantities of hematopoietic factors that are known to be important are present in the recommended daily dose.


One capsule twice a day. (Two capsules daily produce a standard response in the average uncomplicated case of pernicious anemia.)


Capsule, ruby red and opaque scarlet; imprinted E 5380, available in 10 x 10 unit dose packages.


Store at controlled room temperature 15°-30°C (59°-86°F). Protect from moisture.

Rx only

Side Effects & Drug Interactions


Rarely, iron in therapeutic doses produces gastrointestinal reactions, such as diarrhea or constipation. Reducing the dose and administering it with meals will minimize these effects in the iron-sensitive patient.

In extremely rare instances, skin rash suggesting allergy has been noted following the oral administration of liver-stomach material. Allergic sensitization has been reported following both oral and parenteral administration of folic acid.


No information provided.

Warnings & Precautions


Accidental overdose of iron-containing products is a leading cause of fatal poisoning in children under 6. Keep this product out of the reach of children. In case of accidental overdose, call a doctor or poison control center immediately.




Anemia is a manifestation that requires appropriate investigation to determine its cause or causes. Folic acid alone is unwarranted in the treatment of proof vitamin B12 (liver-stomach concentrate with intrinsic factor) deficiency states, such as pernicious anemia.

Folic acid may obscure pernicious anemia in that the blood picture may revert to normal while neurological manifestations remain progressive.

As with all preparations containing intrinsic factor, resistance may develop in some cases of pernicious anemia to the potentiation of absorption of physiologic doses of VITAMIN B12 (liver-stomach concentrate with intrinsic factor) . If resistance occurs, parenteral therapy, or oral therapy with so-called massive doses of VITAMIN B12 (liver-stomach concentrate with intrinsic factor) may be necessary for adequate treatment of the patient. No single regimen fits all cases, and the status of the patient observed in follow-up is the final criterion for adequacy of therapy. Periodic clinical and laboratory studies are considered essential and are recommended.


Pregnancy Category C: Animal reproduction studies have not been conducted. It is also not known whether this product can cause fetal harm when administered to a pregnant woman or can effect reproduction capacity. It should be given to a pregnant woman only if clearly needed.

Nursing Mothers

It is not known whether this drug is excreted in human milk. Because many drugs are excreted in human milk, caution should be exercised when this product is administered to a nursing woman.

Pediatric Use

Safety and effectiveness in children below the age of 10 have not been established.

Overdose & Contraindications



Those of iron intoxication, which may include pallor and cyanosis, vomiting, hematemesis, diarrhea, melena, shock, drowsiness, and coma.


For specific therapy, exchange transfusion and chelating agents. For general management, gastric and rectal lavage with sodium bicarbonate solution or milk, administration of intravenous fluids and electrolytes, and use of oxygen.


Hemochromatosis and hemosiderosis are contraindications to iron therapy.

Clinical Pharmacology


VITAMIN B12 (liver-stomach concentrate with intrinsic factor) with Intrinsic Factor

When secretion of intrinsic factor in gastric juice is inadequate or absent (e.g., in Addisonian pernicious anemia or after gastrectomy), VITAMIN B12 (liver-stomach concentrate with intrinsic factor) in physiologic doses is absorbed poorly, if at all. The resulting deficiency of VITAMIN B12 (liver-stomach concentrate with intrinsic factor) leads to the clinical manifestations of pernicious anemia. Similar megaloblastic anemias may develop in fish tapeworm (Diphyllobothrium latum) infection or after a surgically created small-bowel blind loop; in these situations, treatment requires freeing the host of the parasites or bacteria that appear to compete for the available VITAMIN B12 (liver-stomach concentrate with intrinsic factor) . Strict vegetarianism and malabsorption syndromes may also lead to VITAMIN B12 (liver-stomach concentrate with intrinsic factor) deficiency. In the latter case, parenteral therapy, or oral therapy with so-called massive doses of VITAMIN B12 (liver-stomach concentrate with intrinsic factor) , may be necessary for adequate treatment of the patient.

Potency of intrinsic factor concentrates is determined physiologically i.e., by their use in patients with pernicious anemia. The liver-stomach concentrate with intrinsic factor and the vitamin B12 (liver-stomach concentrate with intrinsic factor) contained in 2 capsules provide 1½ times the minimum amount of therapeutic agent, which, when given daily in an uncomplicated case of pernicious anemia, will produce a satisfactory reticulocyte response and relief of anemia and symptoms.

Concentrates of intrinsic factor derived from hog gastric, pyloric, and duodenal mucosa have been used successfully in patients who lack intrinsic factor. For example, Fouts et al. maintained patients with pernicious anemia in clinical remission with oral therapy (liver extracts or intrinsic factor concentrate with VITAMIN B12 (liver-stomach concentrate with intrinsic factor) ) for as long as 29 years.

After total gastrectomy, Ficarra found multifactor preparations taken orally to be just as effective in maintaining blood levels as any medication that has to be administered parenterally. His study was based on 24 patients who had survived for 5 years after total gastrectomy for cancer and who had been taking 2 capsules daily.

Folic Acid

Folic acid deficiency is the immediate cause of most, if not all, cases of nutritional megaloblastic anemia and of the megaloblastic anemias of pregnancy and infancy; usually, it is also at least partially responsible for the megaloblastic anemias of malabsorption syndromes, e.g., tropical and nontropical sprue.

It is apparent that in VITAMIN B12 (liver-stomach concentrate with intrinsic factor) deficiency (e.g., pernicious anemia), lack of this vitamin results in impaired utilization of folic acid. There are other evidences of the close folic acid-VITAMIN B12 interrelationship:

  1. VITAMIN B12 (liver-stomach concentrate with intrinsic factor) influences the storage, absorption, and utilization of folic acid, and
  2. as a deficiency of VITAMIN B12 (liver-stomach concentrate with intrinsic factor) progresses, the requirement for folic acid increases. However, folic acid does not change the requirement for VITAMIN B12 (liver-stomach concentrate with intrinsic factor) .


A very common anemia is that due to iron deficiency. In most cases, the response to iron salts is prompt, safe, and predictable. Within limits, the response is quicker and more certain to large doses of iron than to small doses. Each capsule furnishes 110 mg of elemental iron (as ferrous fumarate) to provide a maximum response.

Ascorbic Acid

Vitamin C plays a role in anemia therapy. It augments the conversion of folic acid to its active form, folinic acid. In addition, ascorbic acid promotes the reduction of ferric iron in food to the more readily absorbed ferrous form. Severe and prolonged vitamin C deficiency is associated with an anemia which is usually hypochromic but occasionally megaloblastic in type.

Medication Guide



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