Factor v Leiden Question: “I had a blood clot in my leg (DVT) due to elevated homocysteine levels. My doctor wants me to go take a folic acid vitamin pill. I went to the drug store and was a little overwhelmed – they have so many different folic acid tablets. What dose should I be taking?

A: 2.5 mg of folic acid often successfully lowers elevated homocysteine levels. An even better result can be obtained by taking a combination of folic acid, vitamin B6 and vitamin B12. Tablets containing a combination of these exist, making it easy to take the appropriate doses.

What is homocysteine?
Homocysteine is a chemical present in the blood. It is a breakdown product of the amino acid methionine, which we take in with our food. Homocysteine is normally excreted in the urine.

Why do some people have elevated levels?
Some people have an inherited reason to have elevated homocysteine levels (for example a mutation in the MTHFR enzyme, called homozygous MTHFR mutation – see also Q/A 51); other people have a deficiency in vitamin B12 or folate that results in elevated homocysteine levels. Patients with renal failure often have elevated levels; and in yet in other patients we do not know why their levels are high.

Elevated homocysteine levels in the blood can be classified as follows:

  • Less than 13 µmol/L = Normal
  • 13-30 µmol/L = Slightly elevated
  • 30-60 µmol/L = Moderately elevated
  • Greater than 60 µmol/L = Severely elevated

What do elevated levels do?
Elevated levels of homocysteine have been shown to increase the risk for:

  • Atherosclerosis (= hardening of the arteries), that may lead to heart attack and stroke;
  • Blood clots in the legs and veins (venous thromboembolism, such as deep venous thrombosis [DVT] and pulmonary embolism [PE]).

It is not understood how elevated homocysteine leads to blood vessel damage or blood clots.

How can you lower homocysteine levels?
Folic acid, vitamin B6, and vitamin B12 are involved in breaking down homocysteine in the blood. Therefore, taking folic acid, B6, and B12 may help lower the homocysteine level. It is not know whether lowering elevated homocysteine levels really leads to a lowering of the risk of blood clots and hardening of the arteries. However, many physicians recommend that homocysteine levels be normalized, since folic acid, vitamin B6, and vitamin B12 appear to be safe treatments.

The following chart contains information about prescription medications that combine folic acid, B6, and B12 into one tablet that can be taken once a day. This is the easiest way to normalize elevated levels.

Brand nameFolic AcidVitamin B6 = pyridoxineVitamin B12 = cyanocobalaminApproximate Monthly CostGeneric available
Foltx®2.5 mg25 mg1000 mcg$20.69Yes
Folbee*2.5 mg25 mg1000 mcg$12.49
Folgard® Rx 2.22.5 mg25 mg1000 mcg$14.01No

*generic for Foltx®

Regular non-prescription multiple vitamins are typically not sufficient, since they contain much less folic acid, B6 and B12, such as, for example:

Brand nameFolic AcidVitamin B6 = pyridoxineVitamin B12 = cyanocobalaminApproximate Monthly CostGeneric available
Centrum®0.4 mg2 mg6 mcg$ 2.40Yes
Theragran M ®0.4 mg2 mg12 mcg$ 1.50Yes
Folgard®0.8 mg10 mg115 mcg$ 6.50No
B complex vitamin0.4 mg100 mg100 mcg$ 4.80Yes

Pharmacies sell non-prescription folic acid, B6 and B12 as separate vitamins. An acceptable alternative to the prescription combinations would be to take 3 separate tablets of folic acid, vitamin B6 and vitamin B12. While this is a little cumbersome, since one has to take several different tablets a day, it is the least expensive method.

  Ingredients per tablet   
NameFolic AcidVitamin B6 = pyridoxineVitamin B12 = cyanocobalaminNumber of tablets per dayApproximate Monthly Cost
vitamin B650 mg1$ 0.90
vitamin B121000 mcg1$ 1.50
folic acid0.8 mg(= 800 mcg)3$ 1.65
   Total per month $ 6.25

There are many tablet strengths. Be sure to read the label and find the correct strength.


This Q/A was prepared in collaboration with Dr. Caron Misita, pharmacist in the University of North Carolina Thrombophilia Program.


The information contained on the this web site is provided for your general information only. I am not a doctor and I do not give medical advice or engage in the practice of medicine. I do not recommend any particular treatment/trial for individuals, and in all cases recommend that you consult your physician or local treatment center before pursuing any course of treatment. It is up to you, as a consumer to find out if these trials posted are something you want to participate in. I just post the information.

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