Folic Acid Tablets: Strengths, Timing and Safe Use

Folic acid is the form of vitamin B9 used in tablets and fortified foods. Your body needs folate to make new cells, including red blood cells, and it matters most just before and in the first weeks of pregnancy. This guide covers the practical side of tablets: what strength to look for, when to take them and which checks keep you safe. For the wider picture of who needs folic acid, see our guide to folic acid benefits and safety.

Why timing matters before pregnancy

The baby's brain and spine begin forming in the first weeks of pregnancy, often before a pregnancy test turns positive. Folic acid taken before conception and in early pregnancy lowers the risk of neural tube defects. The NIH Office of Dietary Supplements advises 400 micrograms (mcg) of folic acid a day for anyone who could become pregnant, and the NHS advises continuing it until week 12 of pregnancy.

If you have only just found out you are pregnant, start the recommended tablet now and tell your antenatal team. Taking several tablets at once does not make up for missed weeks.

A doctor may advise a higher dose if you have diabetes, take certain medicines or had a previous pregnancy affected by a neural tube defect. Ask which strength is right for you rather than choosing one yourself.

Other reasons a doctor may prescribe it

Folic acid is also used to treat folate-deficiency anaemia and alongside some medicines that affect folate. The dose and schedule for these uses can be very different from a pregnancy tablet.

If you take methotrexate, folic acid is often prescribed to reduce its side effects, usually on set days. Follow your own prescriber's schedule exactly and do not copy anyone else's.

Tiredness alone does not prove a folate deficiency. Low iron, low vitamin B12, thyroid problems and other conditions cause similar symptoms, so get tested instead of guessing with a high-dose tablet.

How to read the strength on the pack

Packs list folic acid in micrograms (mcg or µg) or milligrams (mg). 1 mg equals 1,000 mcg, so 400 mcg is 0.4 mg. A 5 mg tablet contains more than 12 times as much as a 400 mcg tablet, so the two are not interchangeable.

Next, check what else you take. Prenatal vitamins and many multivitamins already contain folic acid. If you are unsure whether to combine products, show both labels to a pharmacist or doctor.

Taking it day to day

• •Swallow the tablet whole with a glass of water at a time you will remember, such as after breakfast.
• •If it makes you feel slightly sick, try taking it with food.
• •If you miss a dose, take it as soon as you remember, then take the next dose at the usual time. Never take two doses together.
• •If vomiting in pregnancy makes tablets hard to keep down, ask your care team about alternatives rather than stopping.

Food still matters

Dal, rajma, chana, peas and leafy greens provide natural folate, along with protein, iron and fibre that a tablet cannot supply. Moong dal with rice, a chana salad or cooked palak at dinner are easy ways to include them. Our list of folic acid rich foods has more ideas. For pregnancy protection, though, food alone is not a reliable substitute for the recommended tablet.

Safety: more is not better

High doses of folic acid can correct the anaemia caused by vitamin B12 deficiency while nerve damage continues unnoticed. This matters if you eat few or no animal foods, are older, or have numbness, tingling, balance problems or memory changes. Folate and B12 are different nutrients, so read our guide to vitamin B12 deficiency if this applies to you.

Folic acid will not fix hair fall, tiredness or fertility problems unless a folate deficiency is the cause. Do not continue a high-dose tablet for months without a review.

Editorial sources

• •NIH Office of Dietary Supplements: Folate fact sheet for consumers
• •NHS: How and when to take folic acid
• •NHS: Methotrexate
• •NHS: Vitamin B12 or folate deficiency anaemia
• •MedlinePlus: Folic acid