Is Green Tea Extract Safe to Take with Antibiotics?

Antibiotics are a broad range of medications used to treat infections stemming from bacterial and fungal sources, as well as parasites. Green tea extract contains antioxidant substances called polyphenols, which have the potential to protect your body's cells from damage caused by molecules known as free radicals. Use of green tea extract in combination with antibiotics called quinolone antibiotics can trigger medically unwanted reactions in your body. Consult your doctor before using this combination.

Hands holding a bowl of green tea.
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Quinolone Antibiotics

Quinolone antibiotics, also called fluoroquinolones, are classified as broad-spectrum antibiotics, which means they can help fight off a wide range of potentially harmful organisms. They have particular usefulness in people who have various forms of pneumonia. Additional potential uses include treatment of other forms of respiratory infection, as well as infections in your urinary tract or skin. Doctors sometimes use medications in this class instead of penicillin and another antibiotic called cephalosporin. Common quinolone antibiotics include ciprofloxacin, norfloxacin, sparfloxacin, trovafloxacin, enoxacin, lomefloxacin, cinoxacin and nalidixic acid.

Green Tea Extract

Green tea extracts are concentrated products derived from unfermented leaves of the Camellia sinensis plant. Compared to other products derived from this species, including oolong and black teas, green tea contains higher amounts of antioxidant polyphenols. In turn, standardized green tea extracts contain specific, known quantities of these substances. While green tea and extract both contain six different polyphenols, most of their activity comes from a single polyphenol, called epigallocatechin gallate, or EGCG. Proposed uses for EGCG-containing tea and extract include treatment or prevention of diseases or conditions that include hardening of the arteries, diabetes, liver disease, high cholesterol and certain forms of cancer.

Potential Interactions

When you take quinolone antibiotics, they can interfere with your body's normal ability to break down caffeine and eliminate it from your system, according to MedlinePlus. Along with its active EGCG content, green tea extract contains significant amounts of caffeine. If you take green tea and a quinolone antibiotic at the same time, the combination of increased caffeine intake and reduced caffeine processing can potentially lead to the onset of side effects that include heart rate increases, headache and jitteriness.


MedlinePlus characterizes the risks for interaction between green tea and quinolone antibiotics as moderate, and urges caution when using these combinations. If you take antibiotics from another group called beta-lactams, use of green tea or green tea extract may increase the effectiveness of these medications by further reducing the resistance of the targeted bacteria. Members of the beta-lactam family include penicillin, cephalosporin and aminopenicillin. Before you consider combining green tea or green tea extract with any antibiotic medication, speak with your doctor.

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