Amoxicillin 875 mg is a high-strength antibiotic tablet used to treat bacterial infections of the respiratory tract, ears, sinuses, skin, urinary tract, and teeth. It belongs to the penicillin family and is one of the most commonly prescribed antibiotics in the United States. The 875 mg strength is typically reserved for more severe infections or for lower respiratory infections of any severity, and it’s taken twice a day rather than the three-times-daily schedule used with lower-strength tablets.
Infections Treated With the 875 mg Dose
The FDA specifically approves the 875 mg tablet for severe ear, nose, and throat infections, severe skin infections, and lower respiratory tract infections (both mild and severe). In practice, though, prescribers use this dose across a broader range of bacterial infections where a stronger concentration is needed to clear the bacteria effectively.
The most common reasons you might be prescribed amoxicillin 875 mg include:
- Sinus infections (sinusitis): Bacterial sinus infections that haven’t improved on their own are frequently treated with 875 mg twice daily for 5 to 10 days.
- Lower respiratory infections: This includes bacterial bronchitis and community-acquired pneumonia caused by susceptible bacteria.
- Severe ear infections: When a standard dose isn’t sufficient or the infection is particularly aggressive.
- Skin and soft tissue infections: Cellulitis, wound infections, and other bacterial skin conditions caused by strep or staph bacteria.
- Urinary tract infections: Caused by common urinary bacteria like E. coli.
- Dental infections: The 875 mg dose is a first-line treatment for dental abscesses and other oral infections.
Amoxicillin 875 mg is also used as part of a combination regimen to treat stomach ulcers caused by H. pylori, the bacterium responsible for most peptic ulcers. In that case, it’s paired with other medications that reduce stomach acid and a second antibiotic.
How Amoxicillin Works
Amoxicillin kills bacteria by interfering with their ability to build cell walls. Bacteria rely on a rigid outer layer called peptidoglycan to maintain their structure and survive. Amoxicillin mimics a building block that bacteria use to assemble this wall, slotting into the construction site and blocking the enzymes responsible for linking the wall together. Without an intact cell wall, the bacteria can’t hold themselves together and die. This mechanism works against both major categories of bacteria, which is why amoxicillin is effective against such a wide range of infections.
Why 875 mg Instead of a Lower Dose
Amoxicillin comes in several strengths, including 250 mg, 500 mg, and 875 mg tablets. The 875 mg dose delivers a higher concentration of the drug into your tissues, which matters when an infection is more severe or involves bacteria that need a stronger push to eliminate. Lower respiratory infections, for example, call for the 875 mg dose regardless of severity because the drug needs to reach effective levels deep in lung tissue.
The higher dose also allows for a simpler schedule. Instead of taking 500 mg three times a day, you take 875 mg twice a day. The total daily amount is similar, but twice-daily dosing is easier to stick with, and consistency matters for clearing an infection completely.
What to Expect While Taking It
A typical course of amoxicillin 875 mg lasts between 5 and 14 days depending on the type and severity of the infection. Sinus infections usually require 5 to 10 days. You can take it with or without food, though eating something beforehand can reduce stomach upset.
The most common side effects are digestive: diarrhea, nausea, and occasionally a skin rash. These are usually mild. Diarrhea happens because the antibiotic disrupts the normal bacteria in your gut along with the harmful ones. Taking a probiotic a few hours apart from your dose can help, though the evidence is mixed on how much difference it makes.
If you develop hives, facial swelling, or difficulty breathing, that signals an allergic reaction. People with a known penicillin allergy should not take amoxicillin, since it’s in the same drug family. About 10% of people who report a penicillin allergy turn out to be truly allergic when tested, but this isn’t something to sort out on your own.
Who Should Not Take the 875 mg Tablet
People with significantly reduced kidney function should not take the 875 mg strength. Specifically, if your kidneys filter below 30 mL per minute (a measure your doctor can check with a simple blood test), the 875 mg dose can build up to unsafe levels because your body can’t clear the drug fast enough. A lower dose or different schedule would be used instead.
Amoxicillin also won’t work against viral infections. If your sinus congestion, sore throat, or cough is caused by a cold or flu virus, this antibiotic won’t help and can contribute to antibiotic resistance. Most upper respiratory infections are viral, which is why doctors sometimes recommend watchful waiting before prescribing antibiotics for conditions like sinusitis. The 875 mg tablet is reserved for situations where a bacterial cause is likely or confirmed.
Children and the 875 mg Dose
Children are dosed by weight rather than given a fixed tablet size. The 875 mg tablet is the usual maximum single dose for pediatric patients and is appropriate once a child weighs roughly 88 pounds (40 kg) or more. Below that weight, liquid formulations allow for precise dosing based on the child’s size. For dental infections in children, the target dose works out to about 22.5 mg per kilogram of body weight per dose, with 875 mg as the ceiling.