What are systemic antibiotics?

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Last updated: May 22, 2025View editorial policy

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From the Guidelines

Systemic antibiotics are medications that are taken orally or administered intravenously to treat bacterial infections throughout the body, and are indicated for use in patients with cellulitis who exhibit systemic signs of infection, such as fever, chills, or tachycardia, as recommended by the Infectious Diseases Society of America 1.

Key Points

  • Systemic antibiotics enter the bloodstream and circulate throughout the body to fight infections in various organs and tissues.
  • Common systemic antibiotics include amoxicillin, ciprofloxacin, azithromycin, and doxycycline, which work by either killing bacteria or preventing their growth through various mechanisms such as inhibiting cell wall synthesis, protein synthesis, or DNA replication.
  • The choice of antibiotic and duration of treatment depend on the severity of the infection, the presence of underlying medical conditions, and the results of culture and susceptibility testing, as outlined in the guidelines for the diagnosis and management of skin and soft tissue infections 1.
  • For patients with severe or complicated skin and soft tissue infections, hospitalization and intravenous antibiotic therapy may be necessary, with options including vancomycin, linezolid, and daptomycin, as recommended by the Infectious Diseases Society of America 1.

Important Considerations

  • Systemic antibiotics should only be used when prescribed by a healthcare provider for confirmed or strongly suspected bacterial infections, and not for viral illnesses like colds or flu.
  • Overuse of antibiotics can lead to antibiotic resistance, making it essential to use these medications judiciously and only when necessary.
  • Patients taking systemic antibiotics should be aware of potential side effects, such as diarrhea, nausea, or allergic reactions, and should complete the full prescribed course of treatment even if symptoms improve, as recommended by the guidelines for the diagnosis and management of skin and soft tissue infections 1.

From the FDA Drug Label

Systemic vancomycin exposure may result in acute kidney injury (AKI). The answer is: Systemic antibiotics refer to antibiotics that are distributed throughout the body via the bloodstream, such as vancomycin, and can affect various organs and systems. Key points:

  • Systemic exposure can lead to adverse effects, including acute kidney injury.
  • Systemic antibiotics are administered to treat infections throughout the body, not just locally. 2

From the Research

Definition of Systemic Antibiotics

Systemic antibiotics refer to antibiotics that are administered to treat infections throughout the body, rather than just topical treatments for localized infections.

  • They are used to treat serious systemic infections, which can be life-threatening if left untreated 3.
  • Systemic antibiotics can be administered orally or intravenously, depending on the severity of the infection and the patient's condition 3, 4.

Characteristics of Systemic Antibiotics

Systemic antibiotics have several key characteristics, including:

  • A broad spectrum of activity against various pathogens 4, 5.
  • High bioavailability, which allows them to achieve effective concentrations in the bloodstream and tissues 3.
  • The ability to penetrate tissues and reach the site of infection 4, 5.

Examples of Systemic Antibiotics

Some examples of systemic antibiotics include:

  • Beta-lactam antibiotics, such as penicillins and cephalosporins 4, 5.
  • Fluoroquinolones, which are effective against a wide range of bacterial infections 6.
  • Aminoglycosides, such as gentamicin, which are often used in combination with other antibiotics to treat serious infections 7.

Use of Systemic Antibiotics

Systemic antibiotics are used to treat a variety of infections, including:

  • Skin and soft tissue infections 4, 5.
  • Respiratory tract infections 6.
  • Urinary tract infections 6.
  • Infections caused by multidrug-resistant bacteria, such as MRSA 5 and Pseudomonas aeruginosa 6.

References

Guideline

Guideline Directed Topic Overview

Dr.Oracle Medical Advisory Board & Editors, 2025

Research

Oral antibiotic therapy of serious systemic infections.

The Medical clinics of North America, 2006

Research

[Systemic therapy with antibiotics. Overview of important antibiotics in dermatology].

Der Hautarzt; Zeitschrift fur Dermatologie, Venerologie, und verwandte Gebiete, 2014

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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