Indications
Vitamin K (Phytomenadione, vitamin K1) is used to prevent and treat bleeding caused by low vitamin K. This includes vitamin K deficiency bleeding in newborn babies, bleeding or a very high INR in people taking Warfarin or similar blood thinners, and bleeding problems linked to poor absorption of fat, long-term antibiotic use or liver disease. Small amounts of vitamin K (K1 or K2) are also found in multivitamin and bone health supplements.
How It Works
The liver needs vitamin K to make several clotting factors, the proteins that help blood clot. Giving vitamin K restores these factors and reduces bleeding. It also helps proteins that are involved in building bone.
Dosage and Administration
Treatment doses depend on the reason and on blood test results, so tablets and injections are used as prescribed. Newborn babies usually receive a single dose soon after birth, given by a doctor, nurse or midwife. Injections are given by a doctor or nurse. Supplements: follow the dose on the product label.
Interactions
Vitamin K reduces the effect of Warfarin and other coumarin blood thinners. If you take one of these, keep your intake of vitamin K from food and supplements steady, and do not start or stop a vitamin K supplement without asking your doctor. Orlistat, Cholestyramine, mineral oil and long-term antibiotics can lower vitamin K levels.
Contraindications
Allergy to Phytomenadione or any ingredient of the product.
Side Effects
Tablets and supplements are usually well tolerated. Injections may cause pain or swelling at the injection site, flushing or an unusual taste.
Get urgent medical help if you have:
- Difficulty breathing, swelling of the face or throat, a fast heartbeat or collapse during or after an injection.
- Bleeding that does not stop, blood in urine or stools, or vomiting blood.
- Pain, swelling or warmth in a leg, or sudden chest pain and breathlessness, in someone on a blood thinner.
Pregnancy and Lactation
Normal dietary and supplement amounts are safe in pregnancy and breastfeeding. Treatment doses should be used only as prescribed.
Precautions and Warnings
People on blood thinners should only take vitamin K as advised by their doctor, since it can make the blood thinner stop working and raise the risk of clots. In severe liver disease vitamin K may not work well. Injections into a vein are given slowly in hospital because of the rare risk of a severe allergic reaction.
Overdose
Vitamin K1 has low toxicity. In someone taking a blood thinner, too much can block its effect and increase the risk of clots. Contact a doctor for advice.
Therapeutic Class
Fat-soluble vitamin; antidote to coumarin anticoagulants.
Storage
Store below 30°C in a dry place, protected from light (keep ampoules in the outer box), and out of the reach of children. Do not freeze injections.
Prepared by the Oshud Alo team from standard drug references. For information only; always follow your doctor's advice.