Vitamin K : Safety, Part 2

by MedlinePlus

(Page 3 of 3)

Side Effects and Warnings

Gastrointestinal: An unusual taste in the mouth has been rarely reported with vitamin K injections. Liver damage has been reported rarely in infants and children with use of the vitamin K preparation Menadiol (not available in the U.S.). Conditions that interfere with absorption of ingested vitamin K may lead to deficiency, including short gut, cystic fibrosis, malabsorption (various causes), pancreas or gall bladder disease, persistent diarrhea, sprue, or ulcerative colitis.

Skin (Dermatologic): Red, painful swelling at vitamin K injection sites has been reported. A raised, itchy plaque can arise at the injection site which may take 1-2 months to resolve, and can cause a scar. Transient flushing has been reported.

Neurologic: Dizziness has rarely been reported with vitamin K injections.

Blood (Hematologic): Damage to red blood cells causing anemia (hemolysis) has been reported rarely in infants and children with the use of the vitamin K preparation Menadiol (not available in the U.S.). This type of vitamin K should be avoided in people with glucose-6-phosphate dehydrogenase (G6PD) deficiency, because vitamin K may cause hemolytic episodes. Vitamin K deficiency decreases blood factors needed for clotting, and increases the risk of bleeding.

Cancer: Although initial concerns were voiced about the possible cancer risk of universally administering vitamin K by injection to newborns, there is no scientific evidence to support this risk. This is generally considered not to be a concern in the medical community.

Pregnancy and Breastfeeding

Pregnancy: Vitamin K is categorized by the Food and Drug Administration (FDA) as Pregnancy Category C. There is not sufficient scientific evidence in animals or humans to clearly conclude the effects on the fetus. Vitamin K given to mothers soon before birth is generally not recommended. Regular supplementation with vitamin K during pregnancy (beyond normal dietary intake) may increase the risk of jaundice in the newborn.

Birth: The American Academy of Pediatrics recommends administering a single intramuscular injection of vitamin K1 to all newborns to prevent vitamin K deficiency bleeding (VKDB), a potentially life-threatening condition. Excessive amounts of vitamin K supplementation in newborns may lead to serious complications, including hemolytic anemia, hemoglobinuria, kernicterus, brain damage, or death. Reactions may be particularly severe in premature infants.

Breastfeeding: Vitamin K ingested by mothers is generally considered to be safe during breastfeeding. There is very little vitamin K transmitted to infants through breastmilk (as opposed to many infant formulas which do include vitamin K). It is not known if the amount of vitamin K in breastmilk is increased if mothers take vitamin K supplements, but the scientific evidence suggests that this likely would make little if any difference. If an infant formula is used that is not fortified with vitamin K, a physician should be consulted to find another way for the infant to receive vitamin K.

Interactions

Interactions with Drugs

Warfarin (Coumadin): Warfarin is a blood-thinning drug that functions by inhibiting vitamin K-dependent clotting factors. Warfarin is prescribed by doctors for people with various conditions such as atrial fibrillation, artificial heart valves, history of serious blood clot, clotting disorders (hypercoagulability), or placement of indwelling catheters/ports. Usually, blood tests must be done regularly to evaluate the extent of blood thinning, using a test for prothrombin time (PT) or International Normalized Ratio (INR). Vitamin K can decrease the blood thinning effects of warfarin, and will therefore lower the PT or INR value. This may increase the risk of clotting. Therefore, people taking warfarin are usually warned to avoid foods with high vitamin K content (such as green leafy vegetables), and to avoid vitamin K supplements. Conversely, vitamin K is used to treat overdoses or excess anticoagulant effects of warfarin, or to reverse the effects of warfarin prior to surgery or other procedures. Over-the-counter vitamin K1-containing multivitamin supplements disrupt warfarin anticoagulation in vitamin K1-depleted patients. Vitamin K-depleted patients are sensitive to even small changes in vitamin K1 intake.

Antibiotics: Some antibiotics may decrease the bacteria in the human gut (which synthesize a small amount of the human vitamin K requirement). Broad-spectrum antibiotics, particularly sulfonamides such as Bactrim, may lower vitamin K levels, and increase the risk of deficiency in people not ingesting adequate amounts.

Salicylates (aspirin): High doses may increase vitamin K requirements.

Antacids: Sucralfate or high doses of aluminum hydroxide antacids may decrease absorption of fat-soluble vitamins such as vitamin K.

Cholestyramine (Questran), mineral oil: May decrease absorption of oral vitamin K and increase vitamin k requirements.

Quinine, Quinidine: May increase vitamin K requirements.

Dactinomycin: This cancer chemotherapy drug may decrease the effects of vitamin K and increase vitamin K requirements.

Menadiol interactions: Menadiol sodium diphosphase is a form of vitamin K that is not used in the U.S. Multiple drugs may cause complications when taken with Menadiol.

Interactions with Herbs/Supplements

Anticoagulant herbs: Vitamin K may decrease the blood thinning effects of herbs that act like warfarin (Coumadin) in the body by decreasing clotting factors made in the liver. In particular, this may apply to herbs with coumarin constituents, such as alfalfa ( Medicago sativa ), American ginseng ( Panax quinquifolium ), angelica ( Angelica archangelica ), anise ( Pimpinella anisum ), asafetida ( Ferula asafetida ), celery ( Apium graveolens ), chamomile ( Matricaria recutita ), fenugreek ( Trigonella foenum-graecum ), horse chestnut ( Aesculus hippocastanum ), prickly ash ( Zanthoxylum spp), quassia ( Picrasma excelsa ), and red clover ( Trifolium pratense ).

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