Hydroxocobalamin is a form of vitamin B-12. It is used as an antidote to cyanide poisoning. Hydroxocobalamin works by helping cells in the body convert cyanide to a form that can be removed from the body through urination.

Hydroxocobalamin is used in an emergency to treat cyanide poisoning. This type of poisoning can occur if you are exposed to smoke from a house or industrial fire, if you swallow or breathe in cyanide, or if you get cyanide on your skin.

Hydroxocobalamin may also be used for purposes not listed in this medication guide.

If possible before you receive hydroxocobalamin, tell your caregivers if you have:

• high blood pressure;
• heart disease;
• congestive heart failure;
• liver disease;
• kidney disease (or if you are on dialysis); or
• if you have ever had a severe allergic reaction to hydroxocobalamin, Vitamin B12, or cyanocobalamin (Nascobal, Cobolin, Cyomin, and others).

FDA pregnancy category C. Tell your doctor if you are pregnant. It is not known whether hydroxocobalamin will harm an unborn baby. However, the benefits of treating cyanide poisoning may outweigh any risks posed by hydroxocobalamin, for both you and your baby.

It is not known whether hydroxocobalamin passes into breast milk or if it could harm a nursing baby. You should not breast-feed after you have been treated with hydroxocobalamin.

In an emergency situation, it may not be possible before you are treated with hydroxocobalamin to tell your caregivers if you are pregnant or breast feeding. Make sure any doctor caring for your pregnancy or your baby knows you have received this medication.

Use Hydroxocobalamin (Hydroxocobalamin (Injection)) exactly as directed on the label, or as prescribed by your doctor. Do not use in larger or smaller amounts or for longer than recommended.

Get emergency medical help if you have any of these signs of an allergic reaction: hives; chest tightness, difficulty breathing; swelling of your face, lips, tongue, or throat.

You may develop an acne-like skin rash within 1 to 4 weeks after you are treated with hydroxocobalamin. This rash should go away without treatment. Call your doctor if you have a rash that lasts longer than 4 weeks.

Call your doctor at once if you have a serious side effect such as:

• bright red blood in your stools;
• chest pain, fast or uneven heart rate;
• severe shortness of breath, wheezing, gasping for breath, cough with foamy mucus;
• swelling in your feet or ankles;
• a light-headed feeling, like you might pass out; or
• dangerously high blood pressure (severe headache, blurred vision, buzzing in your ears, anxiety, confusion, chest pain, shortness of breath, uneven heartbeats, seizure).

Common side effects may include:

• nausea;
• headache;
• acne, skin rash or redness;
• red coloring of your urine (may last 2 to 5 weeks); or
• pain, swelling, or irritation of your skin where the injection was given.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

If your skin turns red after receiving this medication, avoid exposure to sunlight or tanning beds. Hydroxocobalamin can make you sunburn more easily while your skin is still red. Wear protective clothing and use sunscreen (SPF 30 or higher) until your skin color returns to normal.