Folic acid toxicity

I began taking folic acid yesterday, in preparation for starting methotrexate Friday. The leaflet from the pharmacy said there's no special instructions for taking it (such as with food), and under "SIDE EFFECTS," it just said most people don't experience any side effects while taking this medication. It didn't even bother to list what side effects you might experience if you DID have them.

So I took a 1,000 mg tablet. Can't cause any harm -- it's just a vitamin, right? But within 15 minutes, I started getting a headache, then I began feeling a bit dizzy. After about half an hour, nausea and abdominal pain set in. I was up most of the night with the nausea. Now about 14 hours have passed since I took the pill, and I still feel awful. (I even checked the bottles just make sure the pharmacist had not accidentally put the methotrexate in the folic acid bottle!)

This is so ironic. Nobody told me that the drug I'm supposed to take to prevent MTX side effects could have bad side effects itself. Obviously, 1,000 mg is too high a dose for me (I am a very small person, about the size of a 12-year-old child).

The question is, what now? I can't take the MTX without the folic acid. So I will try again tonight, this time taking only half a tablet (500 mg) at bedtime, with food, along with an anti-nausea pill. I hope that works.

I assume that if I can make it through the first week or two with a half-dose, my body will adjust to it and I'll be able to increase to 1,000. But right now, I just feel terrible.

Has anyone else had a reaction like this? How did you handle it? And why aren't we warned that something like that could happen?

I'm a pretty small person too at 5'1". The only side effect I had from folic acid is that my skin is a little oily. Nothing else. I usually take mine with breakfast along with all my other morning suppliments. Since this happened after your first pill I'd say that either a) you are having a side effect of the medication or b) you came down with a virus of some sort and that's what's making you ill.

Call your Doctor IMMEDIATLY. Its extremley rare By a rteraction to B-12 (folic acid can be serious.......

I think you're referring to the fact that you shouldn't take folic acid if you have a B-12 deficiency because it can mask the symptoms of pernicious anemia. I don't have anemia; my blood work is fine.

I should correct something I said earlier. I should have said the tablets are 1 mg, which is 1,000 mcg.

B-12 is Folic acid....... Third paragraph down refers to the symptoms you are having....

It starts off: "Seek medical attention right away if any of these SEVERE side effects occur when using

It goes on: "Gastrointestinal side effects have been reported rarely. They have included anorexia, nausea, abdominal distention, flatulence, and bitter taste.

Gastrointestinal side effects have been reported among patients with doses of 15 mg/day."

If you are having problems with your dosage, either it is a bug or a SEVERE allergic reaction another dose COULD be bad......

Good news: Taking just half a tablet (500 mcg) of folic acid with food at bedtime worked well. I don't have any nausea at all today. I did wake up at 5 a.m. with a horrible leg cramp and my calf still hurts, but I'd much rather have that than nausea!

So tonight I can go ahead and take MTX for the first time. But since I only took half my dose of folic acid, I'm going to take just half the MTX (2 pills instead of 4). If I can tolerate that, I'll go to 4 pills next week. I'm keeping my fingers crossed that this will go well and won't be as bad as I feared.

I’ve been taking folic acid for a year with MTX but the dose prescribed is 5mg once a week which is far different to the high doses you’ve had… Some of my patients in Renal failure are also on folic acid and again the prescribed dose is 5mg weekly. Both my and the patients in Renal the folic acid is to help nutralise the effect of MTX on red blood cell production and the effects of renal failure on red blood cell production.