Nascobal Warnings and Precautions

Some people who use Nascobal may have an increased risk for complications, including those who have Leber's disease, any type of infection, or low levels of folic acid. There are a number of other precautions for using Nascobal safely, including warnings for people who are taking certain medications and women who are pregnant or breastfeeding.

What Should I Tell My Healthcare Provider?

Talk with your healthcare provider prior to using Nascobal® (cyanocobalamin nasal spray) if you have:
  • Leber's disease (also known as hereditary optic neuropathy), a rare condition that causes loss of vision
  • Any infection, including an upper respiratory tract infection
  • A runny or stuffy nose or seasonal allergies
  • Been told you have low levels of folic acid or iron
  • A habit of drinking alcohol on a regular basis
  • Kidney disease, such as kidney failure (renal failure)
  • Polycythemia vera
  • Any allergies, including to foods, dyes, or preservatives.
Also, let your healthcare provider know if you are:
  • Breastfeeding
  • Pregnant or thinking of becoming pregnant.
You should also tell your healthcare provider about all other medications you are taking, including prescription and nonprescription medicines, vitamins, and herbal supplements.

Specific Precautions and Warnings With Nascobal

Some warnings and precautions to be aware of prior to using this nasal spray include the following:
  • Severe optic nerve damage, which can cause vision loss or blindness, has been reported in people with early Leber's disease (a genetic eye condition) who were given vitamin B12. Talk to your healthcare provider before using Nascobal if you have this condition.
  • Treating certain types of severe anemia too aggressively with vitamin B12 could cause dangerously low blood potassium (hypokalemia), high blood platelets, and possibly even death. Your healthcare provider will likely monitor your potassium and platelet levels during treatment.
  • There have been reports of life-threatening allergic reactions and death occurring in people who received vitamin B12 as an injection. However, these reactions have not been reported with Nascobal use.
  • Some people may have a reduced response to Nascobal, including those who take certain medications or those who have an infection, iron or folic acid deficiency, or a buildup of waste products in the blood (often caused by kidney failure).
  • If you have a sensitivity to cyanocobalamin, your healthcare provider will give you a skin test to make sure you are not allergic to Nascobal before starting treatment.
  • You should know that permanent nerve damage can occur if vitamin B12 deficiency goes untreated for three months or longer. Some people may need to take vitamin B12, as Nascobal or in another form, for their entire lives to prevent B12 deficiency and nerve damage.
  • Folic acid can "mask" a vitamin B12 deficiency (which Nascobal is used to prevent). This means it can make it more difficult to tell you have a B12 deficiency from a simple blood test. Doses of folic acid higher than 0.1 mg a day can correct anemia due to a vitamin B12 deficiency without preventing the nerve damage that can occur from vitamin B12 deficiency. Your healthcare provider will check your folic acid and B12 levels before starting treatment.
  • Vitamin B12, including Nascobal, could improve anemia due to folic acid deficiency, making it more difficult to tell if you have low folic acid levels. Your healthcare provider will check your folic acid and B12 levels before starting treatment.
  • Because it is a form of vitamin B12, Nascobal can expose undiagnosed polycythemia vera, a condition associated with too many red blood cells. Nascobal does not cause the condition, but it can cause the condition to return or become more obvious. This is because Nascobal increases vitamin B12 levels, and low levels of vitamin B12 can suppress the symptoms of polycythemia vera. Symptoms of polycythemia vera may include:
    • Difficulty breathing (especially when lying down)
    • Dizziness
    • Itchiness (especially after a hot bath or shower)
    • Redness, numbness, tingling, or burning of the skin.
  • Nascobal may not work for everyone. Your healthcare provider will monitor your response to treatment using blood tests one month after you start Nascobal, and then every three to six months. If this medicine does not work for you, you may need injectable vitamin B12 treatment instead. Injectable vitamin B12 is normally given into a muscle (as an intramuscular, or IM, injection) once a month.
  • Let your healthcare provider know if you have a runny, stuffy, or itchy nose (such as from a cold or seasonal allergies) during treatment. These symptoms could decrease the amount of Nascobal absorbed into your body through your nose. Your healthcare provider may recommend another form of vitamin B12 until your symptoms improve.
  • This medication comes with a medication guide that describes the correct way to use it. Make sure to read this medication guide each time you get your prescription filled.
  • Nascobal passes through breast milk. If you are breastfeeding or plan to start, discuss this with your healthcare provider prior to using this nasal spray (see Nascobal and Breastfeeding).
  • Nascobal is a pregnancy Category C medication. This means that it may not be safe for use during pregnancy, although the full risks are currently unknown (see Nascobal and Pregnancy).

Nascobal Medication Information

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