Does Co-Amoxiclav Increase Heart Rate?
Co-amoxiclav (amoxicillin-clavulanate) does not directly cause tachycardia or increase heart rate as a primary pharmacological effect. The available evidence does not identify tachycardia or heart rate elevation as a recognized adverse effect of this antibiotic combination.
Evidence Review
Established Adverse Effect Profile
The documented side effects of co-amoxiclav are predominantly gastrointestinal and dermatological:
- Gastrointestinal effects are the most common adverse reactions, including diarrhea (occurring in 15-40% of patients), nausea, and vomiting, which can be reduced by taking the medication with food 1, 2, 3.
- Skin reactions such as rash may occur, consistent with other penicillin-class antibiotics 1, 2.
- The clavulanate component specifically contributes additional adverse effects beyond those seen with amoxicillin alone, but these remain primarily gastrointestinal in nature 4.
Cardiovascular Considerations in Context
While cardiovascular effects are not listed as adverse reactions to co-amoxiclav, the broader antibiotic literature provides important context:
- Macrolide antibiotics (azithromycin, clarithromycin, erythromycin) are specifically associated with QT prolongation and cardiac arrhythmias, particularly in patients with pre-existing cardiac conditions 5.
- Guidelines explicitly recommend avoiding macrolides in favor of beta-lactams like co-amoxiclav when cardiac side effects are a concern, precisely because beta-lactams do not share these cardiac risks 5.
- Quinolone antibiotics also carry cardiac warnings, whereas beta-lactam antibiotics (including amoxicillin-clavulanate) are recommended as safer alternatives from a cardiovascular standpoint 5.
Indirect Mechanisms to Consider
If a patient experiences tachycardia while taking co-amoxiclav, consider these alternative explanations:
- Fever and infection itself commonly causes tachycardia as a physiological response; the underlying infection being treated is the more likely culprit 5.
- Dehydration from antibiotic-associated diarrhea could secondarily lead to compensatory tachycardia 1, 2.
- Allergic reactions (though rare with co-amoxiclav) could present with tachycardia as part of an anaphylactic or anaphylactoid response 1.
- Anxiety related to illness or medication concerns may manifest as increased heart rate 5.
Clinical Bottom Line
Co-amoxiclav does not have direct chronotropic (heart rate-increasing) properties and is not associated with tachycardia in the extensive clinical literature spanning over four decades of use 1, 2, 3. If tachycardia occurs during treatment, investigate the underlying infection, assess for dehydration or allergic reaction, and consider alternative diagnoses rather than attributing it to the antibiotic itself. The cardiovascular safety profile of beta-lactam antibiotics like co-amoxiclav is favorable compared to macrolides and fluoroquinolones, making it a preferred choice when cardiac considerations are relevant 5.