Normal doses are probably safe for most people, but high doses can cause problems. Some people may be more likely to experience problems due to vitamin C. Therefore, you should talk with your healthcare provider prior to taking it if you have:
- Cancer (or a history of cancer)
- Glucose 6-phosphate dehydrogenase deficiency
- Certain problems related to iron, including iron overload, hemochromatosis, thalassemia, or sideroblastic anemia
- Kidney stones
- Sickle cell disease
- Any allergies, including allergies to foods, dyes, or preservatives.
Also, let your healthcare provider know if you are:
- Pregnant or thinking of becoming pregnant (see Vitamin C and Pregnancy)
- Breastfeeding (see Vitamin C and Breastfeeding).
Make sure to tell your healthcare provider about all other medicines you are taking, including prescription and non-prescription medicines, vitamins, and herbal supplements.
(Click Vitamin C Safety for more information, including any available warnings and precautions.)
An overdose is unlikely to cause serious problems, since it is a water-soluble vitamin (which means that any excess is usually excreted through the urine). However, high doses of vitamin C have been reported to cause problems in some people.
(Click Vitamin C Overdose for more information.)