Bactrim vs. Amoxicillin for Ear Infection and Urinary Tract Infection: Important Differences and Potential Risks.

Key takeaways

Sulfamethoxazole/trimethoprim (Bactrim, Septra) and amoxicillin (Amoxil) are both antibiotics used to treat bacterial infections, including urinary tract infections (UTIs) and ear infections. However, they belong to different medication classes. Sulfamethoxazole/trimethoprim is a combination of a sulfonamide and an antifolate, while amoxicillin is a penicillin antibiotic. Sulfamethoxazole/trimethoprim is available in oral and injectable forms, whereas amoxicillin is available as oral tablets, capsules, chewable tablets, and liquid. Both medications can cause side effects like nausea, vomiting, and diarrhea, but sulfamethoxazole/trimethoprim can also cause skin sensitivity to sunlight and changes in blood sugar levels. Amoxicillin is generally safe during pregnancy, while sulfamethoxazole/trimethoprim is not recommended. Additionally, sulfamethoxazole/trimethoprim can interact with warfarin and dofetilide (Tikosyn), whereas amoxicillin can interact with medications like warfarin and allopurinol. Both medications require a prescription and should be taken as directed by your healthcare provider.

Sulfamethoxazole/trimethoprim

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Amoxicillin

(Amoxil)

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Summary for Bactrim

Prescription only

Sulfamethoxazole/trimethoprim (sometimes known as SMZ/TMP) is a combination medication containing an antifolate and sulfa antibiotic. It's used to treat different types of infections, such as urinary tract infections (UTIs), ear infections, and lung infections. This antibiotic has two different brand names, Bactrim and Septra, and it's also available as a lower-cost generic. It's a tablet that's taken by mouth, typically twice daily for most types of infections. This antibiotic also comes as a suspension under the brand name Sulfatrim for people who can't swallow tablets and as an injection for people in the hospital. Common side effects include nausea, diarrhea, and rash.

Indications for Bactrim

Urinary tract infection (UTI)
Lower respiratory tract infection (e.g., Pneumocystis pneumonia, infections related to bronchitis)
Diarrhea caused by Shigella (shigellosis)
Travelers' diarrhea - tablet or liquid only
Ear infections - tablet or liquid only

Pros and Cons for Bactrim

Pros

Treats many types of bacterial infections
Can be given to children as young as 2 months old to treat certain infections
Available as a lower-cost generic

Cons

Can upset your stomach and make your skin more sensitive to the sun
Not the best choice for people with liver or kidney problems
Not recommended if you're pregnant
Can't take if you have a sulfa allergy

Common Side Effects for Bactrim

Nausea
Vomiting
Diarrhea
Loss of appetite
Rash
Hives
Skin sensitivity to sun or light

Warnings for Bactrim

Not for use during pregnancy
Severe allergic reactions and skin reactions
Low platelet counts and risk for bleeding
Diarrhea from Clostridioides difficile infection
Low sodium levels and high potassium levels
Blood cell-related problems
Problems with processing phenylalanine - for people with phenylketonuria (PKU) only

Summary for Amoxicillin

Prescription only

Amoxicillin (Amoxil) is a penicillin antibiotic that's used to treat a wide variety of bacterial infections, such as sinus infections, ear infections, strep throat, and urinary tract infections (UTIs). It's available as oral pills, a chewable tablet, and an oral liquid. Amoxicillin (Amoxil) is well-tolerated, but possible side effects include diarrhea, vomiting, and rash.

Indications for Amoxicillin

Upper respiratory tract infections (ear, nose, and throat infections)
Lower respiratory tract infections (e.g., pneumonia, bronchitis)
Urinary tract infections (UTIs)
Skin infections (e.g., cellulitis)
Helicobacter pylori infection (adults only)

Pros and Cons for Amoxicillin

Pros

Works well to treat many different bacterial infections
Can use for adults and children
Available in many forms (e.g., oral tablet, chewable tablet, capsule, liquid)
Liquid form comes in many different flavors to make it taste better

Cons

Might need to take up to three times per day
Can cause stomach side effects like nausea, vomiting, and diarrhea
Not the best option if you have severe kidney problems
Might not be able to take this medication if you've had a severe allergy to penicillin