When Should IV Antibiotics Be Switched to Oral?

Intravenous antibiotics are typically reserved for deep-seated, life-threatening bacterial infections. Doctors generally switch people to oral antibiotics as their condition improves.

Antibiotics are medications used to help fight bacterial infections by targeting different weaknesses in the microbes, depending on the specific drug and organism. Antibiotics are not effective in treating viral infections such as the common cold and flu. 

Antibiotics come in several different forms:

• Oral: pills, capsules, liquids
• Topical: creams, ointments, lotions, sprays, drops
• Injections: Single injection or intravenous injection

Antibiotics are used to fight infections caused by bacteria. Common bacterial infections that may be treated with antibiotics include:

• Strep throat
• Pneumonia 
• Bladder and kidney infections
• Sexually transmitted infections (STIs) such as gonorrhea and chlamydia
• Some ear and sinus infections
• Skin infections
• Dental infections
• Abdominal infections like colitis or diverticulitis
• Whooping cough

The main groups of antibiotics include: 

• Penicillins 
  • Examples: penicillin and amoxicillin (Amoxil, Trimox)
  • Used to treat a wide variety of infections, including skin chest, and urinary tract infections (UTIs)
• Cephalosporins 
  • Examples: cephalexin (Keflex), cefadroxil (Duricef), cephradine (Velosef)
  • Used to treat a wide variety of infections
  • Some are effective for treating serious infections, such as septicemia and meningitis
• Aminoglycosides 
  • Examples: gentamicin (Garamycin) and tobramycin (Tobrex)
  • Used mostly in hospitals to treat serious illnesses such as septicemia
  • Can cause serious side effects
  • Usually given by injection, but may be given as drops for ear or eye infections
• Tetracyclines 
  • Examples: tetracycline (Sumycin) and doxycycline (Doxy-100, Monodox, Oracea)
  • Used to treat a wide range of infections
  • Commonly used to treat acne and a skin condition called rosacea
• Macrolides 
  • Examples: erythromycin (Ery-Tab, PCE), azithromycin (Zithromax, Zmax), clarithromycin (Biaxin)
  • Used to treat lung and chest infections
  • Used an alternative for people with a penicillin allergy, or to treat penicillin-resistant strains of bacteria
• Lincomycins
  • Examples: clindamycin (Cleocin)
  • Used for treatment of susceptible strains of pneumococci, staphylococci, and streptococci
  • One form is also used to treat malaria
• Sulfonamides (“sulfa” drugs)
  • Examples: sulfamethoxazole/trimethoprim (Bactrim)
  • Frequently cause allergic reactions
• Glycopeptides
  • Examples: vancomycin (Vancocin), telvancin (Vibativ)
  • Usually reserved to treat serious infections caused by MRSA, Streptococcus, or Enterococcus bacteria that are resistant other antibiotics
• Fluoroquinolones 
  • Examples: ciprofloxacin (Cipro), levofloxacin (Levaquin), moxifloxacin (Avelox)
  • Broad-spectrum antibiotics no longer used routinely because of the risk of serious side effects
• Carbapenems
  • Examples: ertapenem (Invanz), doripenem (Doribax), meropenem (Merrem)
  • Usually reserved for severe infections and as a last-resort treatment

Intravenous (IV) antibiotics are used for:

• Severe life-threatening infections, such as sepsis 
• Deep seated infections in parts of the body where oral antibiotics are less effective, such as in the spinal fluid and bone
• Infections resistant to oral antibiotics

There are a number of considerations to take into account when deciding to switch from intravenous (IV) antibiotics to oral antibiotics, including:

• The patient’s response to the treatment
• The patient’s immune status
• Any co-existing illnesses
• Allergies
• The patient’s ability to absorb and tolerate oral medications 
• The bioavailability of the medication 
• The causative agent (bacterium) of the illness 
• Whether an oral antibiotic is effective against a particular infectious agent
• Whether the oral antibiotic will penetrate to the site of infection
• Potential adverse effects 

Patients may be switched from IV antibiotics to oral medications when:

• The patient’s condition has improved
• Fever has improved
• Blood pressure and blood flow is stable
• The patient can tolerate oral intake of medications
• There are no concerns about malabsorption
• There is an appropriate oral antibiotic that acts the same or similarly to the IV drug