Zinc - Keflex (Cephalexin) Interaction
Herbal: Zinc
Also Known As: Chelated Zinc, Zinc Acetate, Zinc Acexamate, Zinc Aspartate, Zinc Chelate, Zinc Chloride, Zinc Citrate, Zinc Gluconate, Zinc Glycinate, Zinc Methionate, Zinc Methionine, Zinc Murakab, Zinc Orotate, Zinc Oxide, Zinc Picolinate, Zinc Sulfate, Zinc Sulphate, Zincum Aceticum
Drug: Cephalexin
Brand names:
Keflex, Keftab, Cephalex, Lexin
Medical Content Editor Dr. Brian Staiger, PharmD
Last updated
Apr 13, 2025
Interaction Details
Cephalexin is classified as belonging to the following category: Cephalexin (Keflex)
Zinc might decrease cephalexin levels by chelating with cephalexin in the gut and preventing its absorption.
A pharmacokinetic study shows that zinc sulfate 250 mg taken concomitantly with cephalexin 500 mg decreases peak levels of cephalexin by 31% and reduces the exposure to cephalexin by 27%. Also, taking zinc sulfate 3 hours before cephalexin decreases peak levels of cephalexin by 11% and reduces the exposure to cephalexin by 18%. By decreasing cephalexin levels, zinc might increase the risk of treatment failure. This effect does not occur when zinc is taken 3 hours after the cephalexin dose. To avoid an interaction, advise patients take zinc sulfate 3 hours after taking cephalexin.
Interaction Rating
Likelihood of Occurrence
ProbableInteraction has not been documented in well-controlled studies, however, the interaction has been demonstrated in some small human studies or in controlled animal studies in conjunction with multiple case reports.
References
- Ding Y, Jia YY, Li F, et al. The effect of staggered administration of zinc sulfate on the pharmacokinetics of oral cephalexin. Br J Clin Pharmacol. 2012 Mar;73(3):422-7.
Zinc Overview
Zinc is a mineral that is essential for the proper functioning of the human body. It is involved in many important physiological processes, including immune system function, wound healing, taste, and smell. Zinc is found in a variety of foods, including meat, seafood, and whole grains, and it is also available as a dietary supplement.
Zinc supplements may be used to treat or prevent zinc deficiency, which can occur due to certain medical conditions, such as gastrointestinal disorders, alcohol abuse, and certain medications. Zinc supplements may also be used for other purposes, such as to boost the immune system, improve acne, and reduce the severity and duration of colds.
There are several different forms of zinc supplements available, including zinc gluconate, zinc acetate, and zinc sulfate. The most common form of zinc supplements is zinc gluconate, which is well absorbed and is less likely to cause stomach-related side effects than other forms of zinc.
Cephalexin Overview
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Cephalexin is used to treat certain infections caused by bacteria such as pneumonia and other respiratory tract infections; and infections of the bone, skin, ears, , genital, and urinary tract. Cephalexin is in a class of medications called cephalosporin antibiotics. It works by killing bacteria.
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Antibiotics such as cephalexin will not work for colds, flu, or other viral infections. Using antibiotics when they are not needed increases your risk of getting an infection later that resists antibiotic treatment.
Zinc - More Interactions
Zinc interacts with 52 drugs
Interaction Rating Key
These severity listings are for informational use only. Never start, stop or otherwise change your therapy before speaking with your provider.
| Major | The combined use of these agents is strongly discouraged as serious side effects or other negative outcomes could occur. |
| Moderate | Use cautiously under the care of a healthcare professional or avoid this combination. A significant interaction or negative outcome could occur. |
| Minor | Be aware that there is a chance of an interaction. Watch for warning signs of a potential interaction. |
| Unknown | No interactions have been reported or no interaction data is currently available. |
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Parts of this content are provided by the Therapeutic Research Center, LLC.
DISCLAIMER: Currently this does not check for drug-drug interactions. This is not an all-inclusive comprehensive list of potential interactions and is for informational purposes only. Not all interactions are known or well-reported in the scientific literature, and new interactions are continually being reported. Input is needed from a qualified healthcare provider including a pharmacist before starting any therapy. Application of clinical judgment is necessary.
© 2021 Therapeutic Research Center, LLC
Drug descriptions are provided by MedlinePlus.
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In addition to being a clinical pharmacist specializing in pharmacotherapy, Dr. Brian Staiger is a registered herbalist through the American Herbalist Guild. He has combined his passion for pharmacy practice with the study of medical ethnobotany to improve patient care. Feel free to reach out about any of your herbal or medication questions!
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