Experiences with
CyanocobalaminCyanocobalamin is not suitable for some people. For example, check with your doctor if you have an allergy to cobalt.
Cyanocobalamin comes as tablets and injections. Supplements also come as capsules, mouth sprays and drops. Always follow the instructions.
Most people do not have any side effects with cyanocobalamin tablets. In rare cases cyanocobalamin can cause a serious allergic reaction.
Taking cyanocobalamin with other medicines, herbal remedies, vitamins or supplements is unlikely to cause problems. Check with a doctor or pharmacist.
Who can take cyanocobalamin
Most adults and children can take cyanocobalamin.
Who may not be able to take cyanocobalamin
Cyanocobalamin is not suitable for everyone. To make sure it's safe for you, tell your doctor before starting to take it if you:
- have ever had an allergic reaction to cyanocobalamin or any other medicine
- have an allergy to cobalt
Dosage and how to take cyanocobalamin
Cyanocobalamin tablets that you get on prescription come in strengths of 50 micrograms (mcg) and 1,000 micrograms.
Cyanocobalamin vitamin B12 supplements that you can buy come as tablets, capsules, mouth sprays and drops. These come in different strengths from 10 micrograms to 1,000 micrograms.
The word microgram is sometimes written with the symbol μ followed by the letter g (μg).
The amount of cyanocobalamin you need depends on the level of vitamin B12 in your blood and why your levels are low. Your doctor or pharmacist will advise you on what dose to take.
For adults with diet-related vitamin B12 deficiency, the usual dose is 50 micrograms to 150 micrograms, taken once a day.
For adults with vitamin B12 deficiency not caused by your diet, the usual dose is one to two 1,000 microgram tablets, taken once or twice a day. This is usually if you cannot have vitamin B12 injections.
In children, the doses may be lower.
If you're taking supplements that you've bought, follow the dosage instructions that come with them.
Changes to your dose
To see how well your tablets are working, your doctor may ask you about symptoms such as tiredness and lack of energy. You may also have regular blood tests to monitor the levels of vitamin B12 in your blood.
Your doctor may want to increase or decrease your dose of cyanocobalamin tablets depending on the level of vitamin B12 in your blood.
How to take it
Swallow prescribed cyanocobalamin tablets whole with a drink of water. Do not chew or break them.
It's usually best to take the tablets on an empty stomach. This means at least 2 hours after a meal or snack and at least 30 minutes before you eat again.
For cyanocobalamin supplements that you buy, follow the instructions that come in the packet.
Serious side effects of cyanocobalamin
As cyanocobalamin contains cobalt, it can cause sensitivity reactions in people who have an allergy to cobalt. Symptoms can start straight away or up to 3 days after having a dose.
Talk to your doctor or call 111 if you get an allergic skin reaction such as a rash or hives.
Cyanocobalamin and pregnancy
Cyanocobalamin is safe to take in pregnancy.
You do not usually need to take vitamin B12 supplements when you're pregnant or breastfeeding, unless your doctor has advised you to. You should be able to get all the vitamins you need if you eat meat, fish, eggs, milk and dairy foods.
Cyanocobalamin and breastfeeding
It's OK to take cyanocobalamin if you're breastfeeding.
Vitamin B12 (including cyanocobalamin) is a natural part of breast milk. Cyanocobalamin does pass into breast milk, but it's unlikely to cause any side effects in your baby.
If you notice that your baby is not feeding as well as usual, or if you have any other concerns about your baby, talk to your midwife, health visitor, doctor or pharmacist as soon as possible.
Cautions with other medicines
Cyanocobalamin is usually safe to take with other medicines, including painkillers.
Some medicines may reduce the amount of cyanocobalamin you absorb from the tablets or from the food you eat. This will not usually have a noticeable effect. However, tell your doctor or pharmacist if you're taking:
- metformin for diabetes
- antacids like Gaviscon
- H2 blockers like ranitidine, cimetidine, famotidine or nizatidine
- proton pump inhibitors (PPIs) like lansoprazole, omeprazole, pantoprazole or rabeprazole
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