Yes — vitamin C actually helps your body absorb iron, and clinicians often recommend taking the two together, but stay within sensible doses and check with your pharmacist, especially if you have an iron-overload condition.
These are not competing drugs — vitamin C enhances iron absorption, so the pairing is intentional rather than risky. The NHS notes that a doctor or pharmacist may recommend taking ferrous sulfate (iron) with orange juice or a vitamin C supplement because vitamin C is believed to increase the amount of iron the body absorbs, and that iron is best taken on an empty stomach. The main concerns are not the combination itself but taking too much iron, or having a condition that causes iron to build up: the NIH Office of Dietary Supplements states that people with hemochromatosis should avoid using iron supplements and vitamin C supplements, and that in people with hemochromatosis high doses of vitamin C could worsen iron overload and damage body tissues.
Take iron on an empty stomach (about 30 minutes before or 2 hours after food) with a vitamin C source like orange juice, and keep tea, coffee, eggs and dairy at least 2 hours apart since they reduce iron absorption. Stay within limits: the adult upper limit for iron from all sources is 45 mg/day (a doctor may prescribe more for a while to treat deficiency), and vitamin C above roughly 2,000 mg/day (the adult upper limit) can cause diarrhea, nausea and stomach cramps; very high intakes may also increase the risk of kidney stones, mainly in people with kidney problems. Watch for iron side effects like constipation, nausea, stomach pain or dark stools. Do NOT use this combination without medical advice if you have haemochromatosis or haemosiderosis, get repeated blood transfusions, have a stomach ulcer or bowel problems, or have anaemia not caused by iron deficiency. Keep iron out of reach of children — accidental overdose is a leading cause of fatal poisoning in young children — and ask your pharmacist if you take other medicines, since iron can interfere with some drugs (for example levodopa and levothyroxine).
This is general reference, not medical advice, and not a guarantee of safety. Interactions depend on your doses, health conditions, and other medicines. Always confirm with your pharmacist or doctor before combining products, and follow the dosing on each label.