Vitamin K is essential for blood clotting, bone health, and much more. Increasing your dietary vitamin K intake is generally safe, but some synthetic forms of this vitamin can be toxic. People taking warfarin need to be particularly cautious. Read on to get the facts about different formulations and potentially dangerous drug interactions. <\/p>\n\n\n\n\n\n\n\n
This list does not cover all possible side effects. Contact your doctor or pharmacist if you notice any other side effects. <\/em><\/p>\n\n\n\n Call your doctor for medical advice about side effects. In the US, you may report side effects to the FDA at 1-800-FDA-1088 or at <\/em>www.fda.gov\/medwatch<\/em><\/a>. In Canada, you may report side effects to Health Canada at 1-866-234-2345.<\/em><\/p>\n\n\n\n The normal doses of dietary vitamin K and oral supplements are generally safe<\/strong>. Doses as high as 10 mg K1 and 45 mg K2 (MK-4) per day have been tested in clinical trials without toxic effects [R<\/a>+].<\/p>\n\n\n\n However, the following mild side effects have been reported [R<\/a>]:<\/p>\n\n\n\n Skin reactions with itching and redness from vitamin K injections have been reported on rare occasions. They normally resolved within a few weeks. Severe reactions to injected vitamin K (anaphylaxis) are even less frequent [R<\/a>, R<\/a>+, R<\/a>+, R<\/a>+, R<\/a>+, R<\/a>+].<\/p>\n\n\n\n 2 studies on over 800 children associated vitamin K injection during labor with leukemia, but further studies couldn\u2019t confirm this finding [R<\/a>, R<\/a>, R<\/a>].<\/p>\n\n\n\n A synthetic vitamin K form (menadione or vitamin K3) caused high blood bilirubin<\/a> in premature babies in an old study, but only at very high injected doses (over 10 mg\/day) [R<\/a>+, R<\/a>].<\/p>\n\n\n\n Due to a lack of safety data, a tolerable upper limit for vitamin K has not been established [R<\/a>]. <\/p>\n\n\n\n No known toxicity has yet been associated with natural forms of vitamin K1 (phylloquinone) or vitamin K2 (menaquinone) [R<\/a>]. <\/p>\n\n\n\n However, toxicity has been reported with a synthetic form of vitamin K3 (menadione) and its derivatives. Vitamin K toxicity is most commonly reported in formula-fed newborns and babies receiving menadione injections [R<\/a>]. <\/p>\n\n\n\n When vitamin K builds up in excessive amounts, it blocks the effects of anticoagulant drugs taken by mouth. Limited data suggest synthetic vitamin K3 (menadione) may also cause the following signs and symptoms of toxicity in newborns [R<\/a>, R<\/a>]:<\/p>\n\n\n\n Menadione has also been linked with liver toxicity and jaundice in animal experiments. Due to these serious safety concerns, it is no longer used in North America [R<\/a>]. <\/p>\n\n\n\n According to preclinical research, menadione may increase oxidative stress in cells and disrupt the activity of glutathione, which is considered to be one of the body’s main natural antioxidants. However, this hasn’t been proven in humans [R<\/a>]. <\/p>\n\n\n\nOral Supplements<\/strong><\/span><\/h3>\n\n\n\n
Injections<\/strong><\/span><\/h3>\n\n\n\n
Synthetic Vitamin K<\/strong><\/span><\/h3>\n\n\n\n
Vitamin K Toxicity<\/strong><\/span><\/h2>\n\n\n\n
Safety Data Overview<\/span><\/h3>\n\n\n\n
The Dangers of Menadione <\/span><\/h3>\n\n\n\n