Taking too much vitamin C is generally not harmful, but it can cause some unpleasant side effects. The recommended daily intake of vitamin C is 75-90 mg for adults, and the upper limit is 2,000 mg per day for all adults. Here are some of the side effects that can occur if you overdose on vitamin C:

• Diarrhea
• Nausea
• Vomiting
• Heartburn
• Stomach cramps
• Insomnia
• Headache
• Fatigue
• Fever
• Kidney stones
• Falsely elevated blood glucose readings, which can be problematic for diabetics

Its important to note that people with hemochromatosis, a condition that causes the body to store excessive amounts of iron, should be extra careful with their vitamin C intake, as too much can worsen their symptoms and lead to body tissue damage.

In summary, while its hard to overdose on vitamin C just by eating foods that contain it, taking large doses of vitamin C supplements can cause some negative side effects. Its best to stick to the recommended daily intake and consult with a doctor before taking any supplements.