Skip to Content

Drug Interaction Report

Drug interactions for the following 2 drug(s):

My Interactions List: (Unsaved) Email Save Start Over
Iron-150 (multivitamin with iron)

Interactions between your drugs


tetracycline multivitamin with iron

Applies to: tetracycline, Iron-150 (multivitamin with iron)

GENERALLY AVOID: The bioavailability of oral tetracyclines and iron salts may be significantly decreased during concurrent administration. Therapeutic failure may result. The proposed mechanism is chelation of tetracyclines by the iron cation, forming an insoluble complex that is poorly absorbed from the gastrointestinal tract. In ten healthy volunteers, simultaneous oral administration of ferrous sulfate 200 mg and single doses of various tetracyclines (200 mg to 500 mg) resulted in reductions in the serum levels of methacycline and doxycycline by 80% to 90%, oxytetracycline by 50% to 60%, and tetracycline by 40% to 50%. In another study, 300 mg of ferrous sulfate reduced the absorption of tetracycline by 81% and that of minocycline by 77%. Conversely, the absorption of iron has been shown to be decreased by up to 78% in healthy subjects and up to 65% in patients with iron depletion when ferrous sulfate 250 mg was administered with tetracycline 500 mg. Available data suggest that administration of iron 3 hours before or 2 hours after a tetracycline largely prevents the interaction with most tetracyclines except doxycycline. Due to extensive enterohepatic cycling, iron binding may occur with doxycycline even when it is given parenterally. It has also been shown that when iron is administered up to 11 hours after doxycycline, serum concentrations of doxycycline may still be reduced by 20% to 45%.

MANAGEMENT: Coadministration of a tetracycline with any iron-containing product should be avoided if possible. Otherwise, patients should be advised to stagger the times of administration by at least three to four hours, although separating the doses may not prevent the interaction with doxycycline.


  1. Gothoni G, Neuvonen PJ, Mattila M, Hackman R "Iron-tetracycline interaction: effect of time interval between the drugs." Acta Med Scand 191 (1972): 409-11
  2. "Product Information. Nuzyra (omadacycline)." Paratek Pharmaceuticals, Inc., Boston, MA.
  3. Campbell NR, Hasinoff BB "Iron supplements: a common cause of drug interactions." Br J Clin Pharmacol 31 (1991): 251-5
  4. Neuvonen PJ, Penttila O "Effect of oral ferrous sulphate on the half-life of doxycycline in man." Eur J Clin Pharmacol 7 (1974): 361-3
  5. Bateman FJ "Effects of tetracyclines." Br Med J 4 (1970): 802
  6. Greenberger NJ "Absorption of tetracyclines: interference by iron." Ann Intern Med 74 (1971): 792-3
  7. Neuvonen PJ, Gothoni G, Hackman R, Bjorksten K "Interference of iron with the absorption of tetracyclines in man." Br Med J 4 (1970): 532-4
  8. "Product Information. Seysara (sarecycline)." Allergan Inc, Irvine, CA.
  9. Neuvonen PJ "Interactions with the absorption of tetracyclines." Drugs 11 (1976): 45-54
  10. Venho VM, Salonen RO, Mattila MJ "Modification of the pharmacokinetics of doxycycline in man by ferrous sulphate or charcoal." Eur J Clin Pharmacol 14 (1978): 277-80
  11. "Product Information. Minocin (minocycline)." Lederle Laboratories, Wayne, NJ.
View all 11 references

Switch to consumer interaction data

Other drug and disease interactions

Drug and food interactions


tetracycline food

Applies to: tetracycline

ADJUST DOSING INTERVAL: Administration with food, particularly dairy products, significantly reduces tetracycline absorption. The calcium content of these foods forms nonabsorbable chelates with tetracycline.

MANAGEMENT: Tetracycline should be administered one hour before or two hours after meals.


  1. "Product Information. Achromycin (tetracycline)." Lederle Laboratories, Wayne, NJ.
  2. "Product Information. Declomycin (demeclocycline)." Lederle Laboratories, Wayne, NJ.

Switch to consumer interaction data


multivitamin with iron food

Applies to: Iron-150 (multivitamin with iron)

Food taken in conjunction with oral iron supplements may reduce the bioavailability of the iron. However, in many patients intolerable gastrointestinal side effects occur necessitating administration with food. Some studies suggest administration of iron with ascorbic acid may enhance bioavailability. Ideally, iron products should be taken on an empty stomach, but if this is not possible, administer with meals and monitor the patient more closely for a subtherapeutic effect.


  1. "Product Information. Feosol Tablets (ferrous sulfate)." SmithKline Beecham, Philadelphia, PA.

Switch to consumer interaction data

Therapeutic duplication warnings

No warnings were found for your selected drugs.

Therapeutic duplication warnings are only returned when drugs within the same group exceed the recommended therapeutic duplication maximum.

Drug Interaction Classification

These classifications are only a guideline. The relevance of a particular drug interaction to a specific individual is difficult to determine. Always consult your healthcare provider before starting or stopping any medication.
Major Highly clinically significant. Avoid combinations; the risk of the interaction outweighs the benefit.
Moderate Moderately clinically significant. Usually avoid combinations; use it only under special circumstances.
Minor Minimally clinically significant. Minimize risk; assess risk and consider an alternative drug, take steps to circumvent the interaction risk and/or institute a monitoring plan.
Unknown No interaction information available.

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

Save Interactions List

You must be signed in to save an Interactions list.

Save Interactions List

Save to My Med List

Add your drug list to My Med List to view medical information in a simple, easy-to-read, personalized format. Automatically receive FDA alerts, drug interaction warnings, plus data on food, allergy & condition interactions.