Co-amoxiclav 625mg is an antibiotic used to treat bacterial infections in the ears, lungs, sinuses, skin, and urinary tract. Each 625mg tablet contains two active ingredients: 500mg of amoxicillin and 125mg of clavulanic acid. The amoxicillin kills bacteria, while the clavulanic acid disables a defense mechanism that some bacteria use to resist antibiotics, making the combination effective against a wider range of infections than amoxicillin alone.
Infections Co-Amoxiclav 625mg Treats
Doctors prescribe co-amoxiclav 625mg for bacterial infections throughout the body. The most common uses include:
- Sinus infections that haven’t responded to simpler antibiotics or that are moderate to severe
- Ear infections, particularly middle ear infections in adults
- Lower respiratory infections such as bacterial bronchitis and some types of pneumonia
- Urinary tract infections caused by resistant bacteria
- Skin and soft tissue infections, including infected wounds and animal bites
Co-amoxiclav is typically chosen over plain amoxicillin when the infection is suspected to involve bacteria that produce enzymes called beta-lactamases. These enzymes break down standard penicillin-type antibiotics before they can work. The clavulanic acid blocks those enzymes, restoring amoxicillin’s ability to kill the bacteria.
How to Take It
The 625mg tablet is typically taken three times a day for adults, with courses commonly lasting 5 to 7 days depending on the type and severity of infection. Your prescriber may adjust this based on your specific situation. Taking the tablet at the start of a meal helps your body absorb the medication better and reduces the chance of stomach upset, which is the most common complaint with this antibiotic.
Finish the full course even if you start feeling better within a few days. Stopping early gives surviving bacteria a chance to multiply and potentially become resistant, which can lead to a harder-to-treat infection coming back.
Common Side Effects
The most frequent side effect is diarrhea, which happens because the antibiotic disrupts the normal balance of bacteria in your gut. Nausea and stomach discomfort are also common, especially if you take the tablet on an empty stomach. Some people develop oral thrush (a white coating in the mouth caused by yeast overgrowth) or vaginal yeast infections, since killing off bacteria can allow yeast to flourish.
Skin rashes can occur and are usually mild. However, a severe rash with blistering, peeling skin, or swelling of the face, lips, or throat is a sign of a serious allergic reaction and needs immediate medical attention.
Who Should Not Take Co-Amoxiclav
Co-amoxiclav is a penicillin-type antibiotic, so anyone with a known penicillin allergy should not take it. This is especially critical for people who have experienced anaphylaxis (a severe whole-body allergic reaction), Stevens-Johnson syndrome, or other serious reactions after taking penicillin or related antibiotics. These individuals should avoid all penicillin-class drugs permanently and be referred to an allergy specialist for evaluation.
People with a history of liver problems caused by co-amoxiclav in the past should also avoid it. The clavulanic acid component can occasionally cause liver inflammation, and this risk increases with repeated exposure in susceptible individuals.
Important Drug Interactions
If you take a blood thinner like warfarin, co-amoxiclav can increase your risk of bleeding. The antibiotic disrupts gut bacteria that produce vitamin K, a nutrient your body needs to form blood clots. This can amplify warfarin’s blood-thinning effect, sometimes significantly. The FDA recommends close monitoring of clotting levels during and shortly after taking co-amoxiclav alongside warfarin.
People taking methotrexate (used for autoimmune conditions and some cancers) should be aware that co-amoxiclav can interfere with how the kidneys clear methotrexate from the body, potentially increasing methotrexate side effects.
There is also a small possibility that co-amoxiclav reduces the effectiveness of hormonal birth control pills. While this interaction affects only a small percentage of women, using a backup contraceptive method during your antibiotic course is a reasonable precaution.
Co-Amoxiclav 625mg vs. Other Strengths
Co-amoxiclav comes in several strengths. The 625mg (500/125mg) version is the standard adult dose for most infections. A higher-strength 1g tablet (875/125mg) exists for more serious infections or when a twice-daily dosing schedule is preferred. A lower dose, 375mg (250/125mg), is sometimes used for milder infections. Notably, the amount of clavulanic acid stays at 125mg per tablet across all adult strengths, since higher amounts increase gut side effects without adding much antibacterial benefit. The difference between strengths is entirely in how much amoxicillin each tablet contains.