If you or your child have been prescribed folic acid, follow your doctor's instructions about how and when to take it.
If you have bought folic acid from a pharmacy or shop, follow the instructions that come with the medicine.
How much folic acid you take and how long you take it for depends on why you need it.
Dose before and during early pregnancy
It is recommended to take folic acid while you're trying for a baby (ideally for 3 months before) and during the first 12 weeks of pregnancy.
The usual dose if you're trying to get pregnant and during the first 12 weeks of pregnancy is 400 micrograms, taken once a day.
Your doctor or midwife may recommend taking folic acid throughout pregnancy, particularly if you are at risk of anaemia or are anaemic.
If you have a higher chance of having a baby with a neural tube defect your doctor will recommended an increased dose of 5mg, taken once a day.
Dose for treating folate deficiency anaemia
To treat anaemia, the usual dose for adults and children over 1 year old is 5mg, taken once a day.
Sometimes the dose is increased to 15mg a day.
If your child is under 12 months old, the doctor will use your child's weight to work out the right dose.
You'll usually take it for 4 months. But if your folate deficiency anaemia is caused by a long-term problem, you may have to take folic acid for longer, possibly for the rest of your life. Do not stop taking folic acid without talking to your doctor.
Dose for preventing folate deficiency anaemia
To prevent anaemia, the usual dose for adults and children aged 12 years and over is 5mg, taken every 1 to 7 days.
The dose may vary depending on your age, diet and any other health conditions you have.
For children under 12, the doctor will use your child's age or weight to work out the right dose.
Dose if you're taking methotrexate
The usual dose for adults and children is 5mg once a week, on a different day of the week to your methotrexate.
Some people take 1mg to 5mg once a day, apart from the day when they take their methotrexate.
You'll usually take folic acid for as long as you take methotrexate. You may have to take it for a long time, possibly for the rest of your life.
Do not stop taking it without talking to your doctor. Stopping means you'll be more likely to get side effects from methotrexate, such as being sick (vomiting) and diarrhoea.
Changes to your dose
Usually your dose will stay the same.
Your dose may go up, however, if you're taking folic acid to prevent or treat anaemia and blood tests show you need a higher dose.
How to take it
You can take folic acid with or without food. Swallow the tablets whole with a drink of water.
If you're taking folic acid as a liquid, it will come with a plastic syringe or spoon to help you measure out the right dose. If you do not have one, ask your pharmacist for one. Do not use a kitchen teaspoon as it will not measure the right amount.
If you forget to take it
Missing 1 or 2 doses probably will not matter. But if you keep forgetting to take your folic acid, or you do not want to take it, speak to your doctor.
If you forget to take folic acid, what to do depends on how often you take it:
- once a day – take your missed dose as soon as you remember, unless it's nearly time for your next dose. In this case skip the missed dose and just take your next dose at the usual time. If you remember on the day you take your methotrexate, wait a day and take your missed dose the following day
- once a week – take your missed dose as soon as you remember, unless you take methotrexate that day. If you remember on the day you take your methotrexate, wait a day and take your missed dose the following day. After this, go back to taking your weekly dose on your usual day
Never take 2 doses to make up for a forgotten one.
If you often forget doses, it may help to set an alarm to remind you. You could also ask your pharmacist for advice on other ways to help you remember to take your medicine.
If you take too much
Folic acid is generally very safe. Taking too much is unlikely to cause any harm.
If you're worried, speak to your pharmacist or doctor.