Folic Acid

What is folic acid?

Folic acid is the synthetic form of folate, a type of vitamin B9, and is essential in the production and maintenance of new cells. Folate is naturally found in leafy greens like spinach and kale, legumes such as lentils and chickpeas, and liver. Certain breads and breakfast cereals are also fortified with folic acid. [1]. 

What is folic acid used for?

Folic acid is used for[1]: 

• Preventing and treating anaemia caused by a folate deficiency, anaemia in pregnancy, anaemia in patients on kidney dialysis, or anaemia caused as a side effect of certain medicines  

• Preventing neural tube defects in pregnancy such as spina bifida, an abnormality of the baby’s spine 

• Preventing side effects of methotrexate, a medication used in rheumatoid arthritis, Crohn’s disease, and psoriasis. 

How does folic acid work?

Folic acid plays a crucial role in the production of DNA as well as healthy red blood cells which carry oxygen around the body[1].  

It also helps with the development of the neural tube (which becomes the brain and spinal cord) in the foetus.  

Who can take folic acid?

Folic acid is suitable for most adults and children, depending on their age. Children's doses are based on age and weight and can vary depending on the condition being treated. 

It may not be suitable for some people, consult a doctor or pharmacist if you: 

• Are allergic to folic acid or any of the ingredients in the medicine  

• Have cancer (unless you also have folate deficiency anaemia) 

• Have pernicious anaemia or any other vitamin B12 deficiencies 

• Are receiving haemodialysis due to kidney failure. 

Please tell your doctor or pharmacist about any conditions you may have before starting folic acid, and always follow the instructions in the Patient Information Leaflet[2]. 

How do you take folic acid?

Folic acid can be swallowed whole with a drink of water, with or without food. It is available in tablets or liquid form[1]. 

 If you are prescribed the liquid form, it is important to use the measuring spoon or oral syringe provided with the medication to ensure you are taking the correct dose. Kitchen teaspoons are not reliable and may lead to incorrect dosing. 

What is the typical dosage of folic acid?

The dose of folic acid depends on what it is used for. Standard dosages are:[1]. 

• Treatment of folate-deficient anaemia in adults and children over 1 year old: 5mg daily. In children under 1 year dosage is established based on weight 

• Prevention on neural tube defects before and during pregnancy until week 12 of pregnancy: 400 micrograms daily. A higher dose of 5mg daily may be required in certain cases 

• Prevention of methotrexate side effects: 5mg once weekly taken on a different day to methotrexate dose. 

 Always follow the dosage on the label or as prescribed by your doctor or pharmacist. 

Can you stop taking folic acid?

Yes, you can, but you should consult your doctor or pharmacist before stopping.   

What do you do if you take too much folic acid?

Folic acid is generally safe, and taking an extra dose is unlikely to cause any harm. If you are concerned talk to your doctor or pharmacist. 

What do you do if you forget to take folic acid?

If you forget a dose of folic acid, take it as soon as you remember, unless it's almost time for your next dose. In that case, skip the missed dose and continue with your regular schedule. Never take 2 doses at the same time. If you take methotrexate do not take your folic acid on the same day, wait until the following day[1]. 

What are the side effects of folic acid?

The most common side effects include[1]: 

• Nausea 

• Bloating or gas 

• Loss of appetite 

Serious side effects, such as a severe allergic reaction (anaphylaxis, with symptoms like swelling, difficulty breathing, or rash), are very rare. If you experience these, call 999 or go to A&E immediately. 

The information provided in the side effects section is not a comprehensive list of all possible side effects associated with this medication. For a complete list of side effects, please refer to the Patient Information Leaflet (PIL) provided with your medication or consult your healthcare professional[2]. 

If you experience any side effects, including those not listed, you are encouraged to report them via the Yellow Card Scheme or contact your doctor, pharmacist, or nurse. This information is intended as a summary for general awareness and does not replace professional medical advice. 

Medicines you can't take with folic acid

Folic acid may interact with[1]: 

• Methotrexate (do not take folic acid on the same day as methotrexate dose)  

• Some antiepileptic medication (phenytoin, phenobarbital, and primidone) 

• Some antibiotics (trimethoprim and sulphonamides, sometimes combined as co-trimoxazole) 

• Some indigestion remedies (allow a two-hour gap between folic acid and indigestion remedies) 

• Some preparations containing zinc such as multivitamins 

• Some medications used to treat cancer (e.g. fluorouracil) 

• Cholestyramine 

• Sulfasalazine 

Always inform your doctor or pharmacist about all medications and supplements you take before you start a new medicine and follow the instructions in the Patient Information Leaflet[2]. 

Frequently asked questions about folic acid

Can I drink alcohol while taking folic acid? 

It’s best to avoid alcohol, as it can interfere with folate absorption[1]. 

Can I drive or ride a bike after taking folic acid? 

Yes, folic acid does not affect your ability to drive, ride a bike, or operate machinery[1]. 

Is folic acid safe while breastfeeding? 

Folic acid passes into breast milk in small amounts that are deemed to be safe for the baby[1]. 

Do I need to take folic acid during pregnancy if I already eat foods that contain folate? 

Yes, you still need to take folic acid as it’s unlikely you will get enough through diet alone[1].

For the official NHS guide to folic acid, visit their website.