How and when 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.