Penicillin vs Bactrim

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For patients with bacterial infections, certain antibiotics that inhibit the growth of bacteria can greatly help in managing symptoms and fighting off the infection. Penicillin and Bactrim are two such antibiotics that are commonly prescribed for bacterial infections. They each work differently to hinder bacterial growth but both have significant effects on clearing up infections within the body. Penicillin functions by interfering with the cell wall synthesis of bacteria causing it to weaken and die eventually. Bactrim, on the other hand, is a combination antibiotic made up of sulfamethoxazole and trimethoprim which inhibits successive steps in the biosynthesis of nucleic acids and proteins essential to many bacteria.

What is Penicillin?

Penicillin, discovered in 1928, was the first antibiotic introduced and has since revolutionized the field of medicine. It is primarily used to treat a wide variety of bacterial infections by inhibiting the growth of bacteria. Bactrim, on the other hand, is a combination drug comprised of two antibiotics: sulfamethoxazole and trimethoprim. Approved by FDA in 1973, it is prescribed for certain types of infections such as urinary tract and ear infections or bronchitis among others.

While Penicillin works by bursting the cell wall thereby killing the bacterium directly, Bactrim prevents bacteria from producing folic acid which is necessary for their growth and multiplication. Neither drug acts upon viruses but they cover different spectra of bacteria which results into them being more effective against different kinds of infections.

It's important to note that allergies are common with both medications but are especially prevalent with Penicillin; while side effects like nausea and skin rashes may occur more frequently with Bactrim due to its dual component nature compared to Penicillin.

What conditions is Penicillin approved to treat?

Penicillin is approved for the treatment of various bacterial infections including:

  • Strep throat and other Streptococcus infections
  • Syphilis, a sexually transmitted infection
  • Prevention or treatment of rheumatic fever

On the other hand, Bactrim (a combination of sulfamethoxazole and trimethoprim) is used to treat:

  • Urinary tract infections
  • Middle ear infections (acute otitis media) in children
  • Chronic bronchitis exacerbations in adults
  • Certain types of diarrhea in adults.

How does Penicillin help with these illnesses?

Penicillin is an antibiotic that kills bacteria by interfering with the ability of bacteria to form cell walls. The cell walls of bacteria are vital for their survival; they keep unwanted substances from entering their cells and stop the contents of their cells from leaking out. Penicillin actively prevents the final cross-linking step, or transpeptidation, in assembly of this macromolecule. This effect weakens the bacterial cell wall, causing it to rupture, thereby killing the bacterium.

Bactrim, on the other hand, is a combination drug consisting of sulfamethoxazole and trimethoprim that inhibits two consecutive steps in the biosynthesis pathway by which bacteria synthesize essential proteins. By blocking these critical enzymes required for bacterial replication and survival, Bactrim effectively stops bacterial growth.

Both antibiotics have different targets but ultimately serve to eliminate harmful infections within patients' bodies.

What is Bactrim?

Bactrim is a brand name for a combination of two antibiotics: sulfamethoxazole and trimethoprim. It works by inhibiting the production of folic acid in bacteria, which they need to produce proteins and DNA. By blocking this process, Bactrim effectively stops bacterial growth and multiplication. This drug was first approved by the FDA in 1973.

As an antibiotic, Bactrim does not work against viral infections like penicillin-resistant strains; instead, it's mainly used to treat certain bacterial infections including urinary tract infections, bronchitis, and ear infections among others. Unlike Penicillin which can cause allergic reactions in some patients due to its beta-lactam structure, allergies to Bactrim are generally less common but can still occur.

The side effects of Bactrim differ from those of penicillin-based drugs as well; while both may cause gastrointestinal disturbances such as nausea or diarrhea, skin rash is more commonly associated with Penicillin whereas photosensitivity (sensitivity to sunlight) might be seen with Bactrim use. The effectiveness on specific types of bacteria would make it a better choice than typical antibiotics such as Penicillins for some patients.

What conditions is Bactrim approved to treat?

Bactrim, a combination of trimethoprim and sulfamethoxazole, is approved for the treatment of:

  • Urinary tract infections (UTIs)
  • Acute otitis media in children
  • Shigellosis
  • Pneumocystis jirovecii pneumonia (a form of lung infection often seen in people with weakened immune systems)
  • Traveler's diarrhea.

How does Bactrim help with these illnesses?

Bactrim is an antibiotic that works by inhibiting bacterial synthesis of dihydrofolic acid, a chemical necessary for the production of several important compounds in bacteria. When compared to penicillin, which primarily targets cell wall formation in bacteria, Bactrim takes a unique approach and interferes with their nutritional processes - disrupting their growth and proliferation. It's particularly effective against infections caused by certain types of bacteria that are resistant to other antibiotics. Because it contains two active ingredients (sulfamethoxazole and trimethoprim), Bactrim can be more potent than typical antibiotics like penicillin; however, this also means there may be increased risks for side effects or allergies. Unlike penicillin, Bactrim might not be suitable if you have kidney disease or folate deficiency due to its unique mode of action.

How effective are both Penicillin and Bactrim?

Penicillin and Bactrim (also known as trimethoprim/sulfamethoxazole) are both essential antibiotics, but they have different targets in the bacterial cell. Penicillin was one of the first antibiotics ever discovered and has a long-established history of efficacy against many Gram-positive bacteria such as Streptococcus pneumoniae. It works by disrupting the synthesis of the bacterial cell wall leading to lysis or death of susceptible bacteria.

Bactrim is actually a combination antibiotic containing two active ingredients: sulfamethoxazole, which stops bacteria from utilizing folic acid for growth, and trimethoprim, which inhibits bacterial enzyme production. This double action gives it broad-spectrum activity against a wide range of Gram-negative and Gram-positive organisms.

Though both antibiotics can be used in treating different types of infections caused by susceptible strains of bacteria, there are certain conditions where one might be preferred over the other due to differences in their antimicrobial spectrum. For example, penicillins are often first-line treatment for streptococcal pharyngitis ("strep throat") while Bactrim may be chosen for urinary tract infections caused by E.coli.

In terms of safety profiles, both drugs have well-established side effect profiles with allergic reactions being more common with penicillins including serious anaphylactic reactions. On the other hand, Bactrim is associated with unique risks like Stevens-Johnson syndrome (a severe skin reaction), hyperkalemia (high blood potassium levels), and possible interactions with medications like warfarin or methotrexate.

It's also worth noting that resistance patterns can affect choice between these two options; some staphylococci are resistant to penicillins but may still respond to Bactrim - this includes MRSA (methicillin-resistant Staphylococcus aureus). Both antibiotics require monitoring during therapy especially if used in patients with pre-existing kidney disease given potential nephrotoxic effects.

abstract image of a researcher studying a bottle of drug.

At what dose is Penicillin typically prescribed?

Oral dosages of Penicillin range from 250-500 mg every 6 hours for adults, but studies have indicated that a dose of 500 mg every 8 hours is generally sufficient for treating mild to moderate infections in most people. Children can be started on a dosage calculated by their body weight - usually around 25-50 mg/kg/day divided into equal doses given every 6 to 8 hours. In either population, dosage might be increased after a few days if there is no response. The maximum dosage that should not be exceeded in any case is around 3 g/day in adults and the corresponding body-weight appropriate dose for children.

Bactrim (a combination of sulfamethoxazole and trimethoprim) typically comes as tablets containing either single strength (400/80mg) or double strength (800/160mg). Adults are usually prescribed one double-strength tablet per day, while children's doses are determined based on weight - approximately at the ratio of six milligrams of trimethoprim and thirty milligrams of sulfamethoxazole per kilogram each day, split into two doses taken twelve hours apart. Dosage may increase depending on the severity or type of infection being treated.

At what dose is Bactrim typically prescribed?

Bactrim treatment typically begins with a dosage of 800 mg sulfamethoxazole and 160 mg trimethoprim by mouth, every 12 hours. This dose can then be adjusted based on the severity of the infection being treated and individual patient response. For severe infections, the dosage may be increased to two tablets every 12 hours, spaced evenly apart. Maximum daily dose is four tablets divided into two doses (each containing 800 mg sulfamethoxazole and 160 mg trimethoprim) taken at an interval of approximately twelve hours. If there's no improvement in symptoms after few days of therapy at standard dosages, your healthcare professional might consider increasing your Bactrim dosage or switch to another antibiotic.

What are the most common side effects for Penicillin?

Common side effects associated with penicillin include:

  • Diarrhea
  • Nausea, vomiting
  • Rash or hives
  • Black tongue
  • Oral thrush (yeast infection in the mouth)
  • Swollen tongue

On the other hand, Bactrim may cause:

  • Nausea/vomiting
  • Loss of appetite
  • Abdominal pain
  • Sensitivity to sunlight
    -Dizziness, headache -Rash or itching. -Low blood sugar levels (hypoglycemia)

Remember that these are not all the possible side effects. If you experience any distressing symptoms while taking these antibiotics, seek immediate medical attention.

abstract image of a patient experiencing side effect

Are there any potential serious side effects for Penicillin?

When comparing Penicillin to Bactrim, it's important to note that while both are antibiotics, they can cause different side effects.

  • Allergic reactions: This is more common with penicillin and includes symptoms like hives, difficult breathing, swelling in your face or throat.
  • Skin reaction: Both drugs can cause a severe skin reaction characterized by fever, sore throat, burning eyes, skin pain and red or purple rash with blistering and peeling.
  • Vision changes: Rarely reported but if you experience blurred vision or tunnel vision; eye pain; seeing halos around lights with either medication seek medical help immediately.
  • Heart-related issues: Fast or pounding heartbeats; fluttering in your chest; shortness of breath and sudden dizziness are rare but serious side effects. If you feel like you might pass out whilst taking these medications contact a health professional straight away.
  • Hyponatremia (low sodium levels): Symptoms may include headache confusion slurred speech vomiting loss of coordination feeling unsteady severe weakness - this is an extremely rare side effect for both Penicillin and Bactrim.
  • Severe nervous system reaction: Very stiff muscles high fever sweating confusion fast uneven heartbeats tremors feeling like passing out - These are not typical side effects of either drug but consult a doctor immediately if experienced.

Any signs resembling serotonin syndrome such as agitation hallucinations shivering muscle stiffness twitching nausea vomiting diarrhea should be taken seriously although again unlikely with these two antibiotics.

What are the most common side effects for Bactrim?

Bactrim, also known as trimethoprim-sulfamethoxazole, can cause a variety of side effects. These may include:

  • Nausea, vomiting or loss of appetite
  • Mild rash or itching
  • Headache, dizziness
  • Insomnia and other sleep problems
  • Increased sensitivity to sunlight causing sunburns easily
  • Muscle or joint pain

It's important to note that some side effects might be serious such as shortness of breath, persistent coughing, abnormal bleeding/bruising and severe allergic reactions. If any discomfort occurs while taking Bactrim, it is recommended to consult your healthcare provider promptly.

Are there any potential serious side effects for Bactrim?

While Bactrim is generally well-tolerated, it can occasionally cause serious side effects. If you experience any of the following symptoms while taking Bactrim, seek immediate medical attention:

  • Signs of an allergic reaction such as difficulty breathing; swelling of your face, lips, tongue or throat.
  • An indication of a severe skin reaction like fever, sore throat, burning in your eyes and skin pain followed by a red or purple skin rash that spreads (especially in the face or upper body) causing blistering and peeling.
  • Unusual bleeding or bruising under the skin.
  • Yellowing of the eyes or skin which may suggest liver problems
  • A sudden onset headache with severe dizziness and fainting spells could indicate blood disorders.
  • Changes in heartbeat patterns: unusually fast/slow/irregular heartbeats are all causes for concern.

Remember to always consult with a healthcare professional when experiencing adverse reactions to medications.

Contraindications for Penicillin and Bactrim?

Both penicillin and Bactrim, like most antibiotics, may cause adverse reactions in some individuals. If you experience severe side effects such as hives, difficulty breathing, or swelling of your face, lips, tongue or throat after taking these medications, seek immediate medical attention.

Neither penicillin nor Bactrim should be taken if you have a history of allergy to either drug. Both drugs can trigger serious allergic reactions in susceptible individuals. Always disclose to your healthcare provider any past experiences of drug allergies; this is crucial in preventing potentially life-threatening allergic reactions.

Penicillin and Bactrim must not be used by those with certain medical conditions without close supervision from a healthcare professional. This includes those with liver disease (for Penicillin) and kidney disease (especially for Bactrim). Inform your doctor about all the current medications you're taking including prescription drugs, over-the-counter products as well as any vitamins or herbal supplements to avoid harmful interactions.

How much do Penicillin and Bactrim cost?

For the brand name versions of these antibiotics:

  • The price for 30 tablets of Bactrim DS (800 mg/160 mg) averages around $170, which works out to approximately $5.60/day.
  • The price for 28 capsules of Penicillin V Potassium (500 mg), a commonly prescribed form of penicillin, is about $23, working out to roughly $0.82/day.

Thus, if you are taking the typical dosage for either antibiotic (usually one or two doses per day), then brand-name Penicillin V Potassium is less expensive on a per-day treatment basis. Please note that cost should not be a primary consideration in determining which of these drugs is right for you.

As far as generic versions go:

  • Sulfamethoxazole/trimethoprim (the active ingredients in Bactrim) costs between $10 and $15 for 20 tablets (800mg/160mg each), translating into daily costs from about $1 to nearly $2 depending on your dose.
  • Generic Penicillin V Potassium can be found at prices ranging from roughly only a few dollars up to about ten dollars per usual course — making it typically cheaper than its counterpart here by quite some margin!

Popularity of Penicillin and Bactrim

Penicillin, in generic form as well as brand names such as Pen-Vee K and V-Cillin K, was estimated to have been prescribed to about 29.5 million people in the US in 2020. Penicillin accounted for roughly 8% of antibiotic prescriptions in the US. As a class of antibiotics, penicillins are historically significant since they were some of the first medications effective against many previously serious diseases like syphilis and Staphylococcus infections.

Bactrim (a combination drug containing sulfamethoxazole and trimethoprim), on the other hand, was prescribed to approximately 20 million people in the USA during the same period. In terms of overall antibiotic market share within America, Bactrim accounts for around 6%. It is particularly useful for treating urinary tract infections and bronchitis but is also utilized against a variety of bacterial infections resistant to other antibiotics. Over recent years we can observe an increase in its usage due to emerging resistance patterns making it a more desirable choice among physicians.


Both penicillin and Bactrim (sulfamethoxazole/trimethoprim) have extensive records of use in treating bacterial infections, with considerable clinical evidence supporting their effectiveness over placebos. Sometimes these antibiotics may be used together, but this requires careful medical supervision due to potential drug interactions. They work differently: penicillin interferes with the cell wall synthesis of bacteria, while Bactrim impedes folic acid production which is needed for DNA replication.

Penicillin is often a first-line treatment option for certain types of infections such as streptococcal pharyngitis or syphilis. For some conditions like urinary tract infections or MRSA skin infections where resistance to penicillins is common, Bactrim might be considered as an initial therapy or an adjunctive therapy to other antibiotics.

Both medications are available generically resulting in significant cost savings especially for patients paying out-of-pocket. The onset of effect can vary depending on the nature and severity of infection.

In terms of side effects profile, both drugs are typically well-tolerated by most individuals; however some people may experience nausea, vomiting or diarrhea from either drug. Penicillin has a relatively lower risk compared to Bactrim for severe adverse reactions like Stevens-Johnson Syndrome although it's more commonly associated with allergic reactions. As always when starting any new medication regimen - including antibiotics - monitoring your body’s response and seeking immediate medical help if you notice signs of allergy or worsening symptoms is crucial.