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Folic Acid

Last updated on 22/03/2021.

Overview   |   Dosage   |    Side Effects   |   Precautions  |   Tips  |   Where To Buy  



BRAND NAME(S) IN HONG KONG: Blackmores Folic Acid, Folic Acid Jamieson, Folic Acid Sunward

DRUG CLASS: Vitamin (water soluble) 

USED FOR: Folic acid deficiency, megaloblastic anemia, prevention of neural tube defects, prevention of Methotrexate-induced side effects

OTHER DRUGS IN THE SAME CLASS: Vitamin B6, Vitamin B12, Vitamin C

– 400mcg, 800mcg (tablets)

What is Folic Acid for?

Folic Acid is a form of vitamin B, which is important for many metabolic processes such as the synthesis of DNA. Deficiency may occur due to malnutrition, malabsorption, pregnancy, excessive loss of Folic Acid, or as a result of the use of drugs that interfere with Folic Acid. Folic Acid can be used in the treatment and prevention of the above conditions to increase Folic Acid levels. Other uses of Folic Acid include folate-deficient megaloblastic anemia, prevention of neural tube defects, and prevention of Methotrexate (a medicine that reduces Folic Acid level) side effects.

How to use it?

For folate-deficient megaloblastic anemia 


Adult / Child 1-17 years

1 to 5 mg daily; For people with malabsorption, doses up to 15 mg daily may be required


For prevention of neural tube defects (in those at a low risk of conceiving a child with a neural tube defect)


Females of childbearing potential

400 or 800 micrograms (0.4 or 0.8 mg) daily, to be taken before conception and until week 12 of pregnancy


For prevention of neural tube defects (in those in the high-risk group who wish to become pregnant or who are at risk of becoming pregnant)


Females of childbearing potential

5 mg daily before conception and until week 12 of pregnancy


For prevention of methotrexate-induced side-effects



1 to 5 mg once daily. Sometimes your doctor will advise you to skip your Folic Acid on the day of your methotrexate dose.

What are the side effects of Folic Acid?

Folic Acid is safe to use but flushing, nausea, abdominal distension, and flatulence, may occasionally occur.

Who should not take Folic Acid?

People allergic to Folic Acid or any component of the formulation.

Pharmacist Tips:

– Folic Acid can also be obtained from natural sources, such as dark green leafy vegetables, beans, liver, whole grains, shellfish and eggs.
– Pregnant women still need to take Folic Acid supplements even if they already eat foods that contain it.

Common dosing schedule:
Folic Acid can be taken with or without food.

This schedule is for reference only, adjustments may be made according to individual needs.

Some common medications Folic Acid may interact with:
Antiepileptics, e.g. Phenytoin, Phenobarbital
– Chemotherapy, e.g. Capecitabine, Fluorouracil

Please notify your doctor or pharmacist if you are taking the above medication, dosage adjustments might be needed.

Where to buy Folic Acid in Hong Kong?

In Hong Kong, Folic Acid is an over-the-counter medicine which can be purchased without a prescription from any retail outlet in Hong Kong. This includes grocery stores, convenience stores, medicine shops, and pharmacies. It can also be obtained from doctors. To find a pharmacy near you, refer to the list of pharmacies (“Authorized Sellers of Poisons”) from the Hong Kong Department of Health. 

For more information about drug names and ingredients, you can visit Hong Kong’s Drug Office at

Need more information?

For detailed information about the use of Folic Acid in children, pregnancy and breastfeeding, and for questions about drug interactions, please check with your pharmacist or doctor.

Disclaimer: our goal is to provide you with the most relevant drug information and common dosage for Hong Kong. This information does not constitute medical advice. For specific treatment recommendations and advice, always discuss with your doctor or pharmacist, and follow the instructions included with your specific medicine.