Folic acid is the man-made version of the vitamin folate (also known as vitamin B9).
It's available on prescription and comes as tablets. You can also buy lower dose tablets from pharmacies and supermarkets.
Brand names include Clonfolic, Sona, and Active Folic. Ask your pharmacist which is best for you.
It's recommended that all women of childbearing age should take a 400mcg folic acid supplement every day, even if they are not planning to get pregnant.
Uses of folic acid
Folic acid is used to:
- treat or prevent folate deficiency anaemia, which impacts on how well your red blood cells work
- help your unborn baby's brain, skull and spinal cord develop properly during pregnancy – this helps to avoid development problems such as spina bifida
- help reduce side effects from methotrexate, a medicine used to treat severe arthritis, Crohn's disease or psoriasis
It's best to take folic acid for at least 14 weeks before you become pregnant, when you're trying for a baby. You should continue taking it for at least the first 12 weeks of pregnancy.
Folic acid can also be taken with:
- ferrous fumarate and ferrous sulphate (to treat iron deficiency anaemia)
- other vitamins and minerals (as a multivitamin and mineral supplement)
Serious allergic reaction
Serious allergic reaction to folic acid is rare. But if you have one you will need to go to the emergency department (ED).
Emergency action required: Call 999 or go to an ED straight away if you:
- get a skin rash that may include itchy, red, swollen, blistered or peeling skin
- are wheezing
- get tightness in the chest or throat
- have trouble breathing or talking
- feel your mouth, face, lips, tongue or throat start to swell
These are warning signs of a serious allergic reaction (anaphylaxis) and you might need to go to hospital.
When you start taking folic acid
Folic acid is absorbed very quickly in the gut once taken.
If you're taking it for folate deficiency anaemia, it may be a few weeks before you start to feel better.
If you're taking it because you're pregnant, you probably will not feel any different, but that does not mean it's not working.
You're unlikely to get side effects with folic acid, but some people feel sick, lose their appetite, get wind or feel bloated. These side effects are usually mild and do not last long.
Do not drink alcohol with folic acid as it may stop folic acid being absorbed.
Check if you can take folic acid
Most adults and children can take folic acid.
To make sure it's safe for you, tell a doctor or pharmacist before you start taking folic acid if you have:
- had an allergic reaction to folic acid or any other medicine in the past
- low vitamin B12 levels (vitamin B12 deficiency anaemia) or pernicious anaemia
- a type of kidney dialysis called haemodialysis
- a stent in your heart
Folic acid and breastfeeding
Folic acid is safe to take while you're breastfeeding. It passes into your milk, but it's not harmful to your baby.
If your baby is premature or has health problems, check with your GP first.
How and when to take it
All women of childbearing age should take folic acid, even if they are not planning to get pregnant.
You usually take folic acid once a day, but sometimes you only need to take it once a week.
Follow your GP's instructions about how and when to take it, if you or your child have been prescribed it.
Follow the instructions that come with the packet, if you have bought folic acid from a pharmacy or shop.
You can take folic acid with or without food. Swallow the tablets whole with a drink.
If you're pregnant or trying for a baby, it's recommended you take folic acid until you're 12 weeks pregnant. It helps your baby grow normally.
All women of childbearing age should take a 400mcg folic acid supplement every day, even if they are not planning to get pregnant.
If you forget to take it
Missing 1 or 2 doses will not matter.
Never take 2 doses to make up for a forgotten one.
If you take folic acid once a day
Take your missed dose as soon as you remember.
If it's nearly time for your next dose, skip the missed dose and just take your next dose as normal.
If you take folic acid 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.
If you take too much
Folic acid is generally very safe. Taking too much is unlikely to harm you or your child.
Speak to a pharmacist or your GP If you're worried.
Side effects of folic acid
Talk to your GP, a pharmacist or nurse if these side effects bother you or do not go away:
- feeling sick (nausea) - but if you're pregnant, this is more likely to be morning sickness
- loss of appetite
- bloating or wind
See the patient information leaflet that comes with your medicine for a full list of side effects.
Non-urgent advice: Find your patient information leaflet
Your patient information leaflet is the leaflet that comes with your medicine. You can find a digital version of the leaflet online.
Report side effects
You can report any suspected side effects to the the Health Products Regulatory Authority (HPRA): report an issue - hrpa.ie
Taking folic acid with other medicines
Some medicines interfere with the way folic acid works. If you’re on any other medicines or supplements, check with your GP, a pharmacist or nurse before you start taking folic acid.
Do not take your folic acid within 2 hours before or after taking indigestion remedies (antacids containing aluminium or magnesium), as they may stop folic acid being properly absorbed.
You can take folic acid at the same time as everyday painkillers, for example paracetamol.
Talk to your GP before taking any non-steroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen or aspirin, if you're taking folic acid with methotrexate.
This content was fact checked by a pharmacist, a GP, the National Medication Safety Programme (Safermeds) and the Health Products Regulatory Authority (HPRA).