How long does it take to correct vitamin deficiency. I’ve had splitting for months and months at the corners mouth. Chronic fatigue and tremors. Doctors tested me for B12 iron and folic. All ok. But I’ve been in a right mess for months. Even had cracking at the corners of my eyes, Also had bowel investigation. I was getting sicker and sicker. So I paid for a gut biome test as this has been going on 2 years in all. It came back I’m low on B2 side effects splitting of the corners of your eyes lips chronic fatigue and nerve damage. My stomach is not processing it. Anyway I’ve started to take vitamin B2 . How long does it take for vitamin deficiencies and damage to be corrected. I’m quite angry because I asked the Doctor if I could be deficient in another vitamin and she said no you’ve had enough tests done. I’ve been drinking through a straw for six months because my lips have been in such a mess.