Ampicillin and Sulbactam (Injection)

Ampicillin and Sulbactam is an injectable medication marketed under the brand name Unasyn that is used to treat severe bacterial infections throughout


Ampicillin and sulbactam combination is a powerful antibiotic injection used to treat a wide variety of serious bacterial infections in many different parts of the body. It is a strong treatment for these infections but is not intended for use to combat colds, flu, or any other kind of viral infection. Its primary effect is to inhibit the growth of bacteria and aid the body's natural process of fighting infection and aid in the healing process. It is a member of the penicillin family of medications as well as a beta-lactamase inhibitor. This injection should only be administered with the direct supervision of your physician.

Ampicillin and Sulbactam are intended for the treatment of skin and skin structure infections due to the presence of the following bacterial organisms: Acinetobacter calcoaceticus, Bacteroides fragilis, Escherichia coli, susceptible, beta-lactamase-producing strains of Staphylococcus aureus, Enterobacter species, Klebsiella species (including K pneumoniae), and Proteus mirabilis. This treatment can be combined with gentamicin or tobramycin as a combination regimen for treatment of incisional surgical site infections. Some gram-negative rods are resistant to this medication and it does not provide coverage for methicillin-resistant S aureus (MRSA).

Conditions Treated

  • Skin or Soft Tissue Infection
  • Skin and Structure Infection
  • Intraabdominal Infection
  • Bacterial Infection
  • Endocarditis
  • Sinusitis
  • Pelvic Inflammatory Disease
  • Surgical Prophylaxis

Type of Medicine

  • Antibiotic

Side Effects

As with any medication, an Ampicillin and Sulbactam injection can induce some undesirable side-effects in addition to its intended effect of fighting bacterial infections. Some of these are serious enough that they may require medical attention in the event that they arise during the course of treatment for infection. Immediate treatment should be sought if any of the following symptoms are experienced.

  • Diarrhea
  • Swelling of the feet or legs
  • Pain and tenderness
  • Change of skin color

While the following side effects are more rarely experienced, their incidence are also cause for concern and your physician should be immediately informed.

  • Burning sensation while urinating
  • Decrease in frequency of urination
  • Decrease in urine volume
  • Difficulty in urination
  • Painful urination
  • Chills
  • Chest pain
  • Bloody nose
  • Swelling
  • Puffiness of the face
  • Flushing
  • Redness of the skin
  • Tightness of the throat

These additional side effects have also been experienced during the course of treatment with Ampicillin and Sulbactam injections, although the incidence of these is not known.

  • Black hairy tongue
  • Sores, ulcers, or white spots on lips or mouth
  • Swelling or inflamation of the mouth
  • Blistering of the skin
  • Peeling or loosening of the skin
  • Scaly skin
  • Cracked skin
  • Red, swollen skin
  • Bloating
  • Coughing
  • Fever
  • Increased thirst
  • Sore throat
  • Bloody stools
  • Itching
  • General feeling of weakness
  • Joint of muscle pain
  • Nausea
  • Vomiting
  • Severe abdominal pain
  • Stomach cramps
  • Joint or muscle pain
  • Lower back or side pain
  • Fatigue
  • Unusual bleeding or bruising
  • Red, irritated eyes
  • Unusual weight loss

Additionally, there are certain side effects that are more routine and not necessarily grounds for concern. These often go away during treatment as the body adjusts to the medication. Ask your physician if you need to alleviate these side effects or if they have been experienced over a long duration.

  • Gas
  • Indigestion
  • Upset stomach
  • Heartburn
  • Warmth at injection site
  • Swelling
  • Tenderness
  • Hives
  • Lumps
  • Soreness
  • Ulceration
  • Tingling
  • Bloated feeling
  • Rashes
  • Headache
  • Swelling of the stomach
  • General discomfort or illness

This is not an exhaustive list and you may experience other side effects. If you notice anything that is not listed immediately inform your healthcare professional as this may be indicative of a greater health problem.


This injectable medication should only be administered under the direct supervision of your physician. It will normally be administered as an intravenous drip by a nurse or other medical professional. For a soft tissue infection, the dose should be 1.5 to 3g IV or IM every 6 hours in a consistent 2:1 ratio of ampicillin to sulbactam. The Infectious Diseases Society of America (IDSA) recommendation for situational infections are as follows:

  • Incisional surgical site infection: 3 g IV every 6 hours
  • Infection after animal bite: 1.5 to 3 g IV every 6 to 8 hours
  • Infection after human bite: 1.5 to 3 g IV every 6 hours
  • Skin and Structure Infection: 1.5 to 3 g IV or IM every 6 hours
  • Intraabdominal Infection: 1.5 to 3 g IV or IM every 6 hours
  • Bacterial Infection: 1.5 to 3 g IV or IM every 6 hours
  • Endocarditis: 3 g IV every 6 hours
  • Sinusitis: 1.5 to 3 g IV every 6 hours
  • Severe infection requiring hospitalization: 1.5 to 3 g IV every 6 hours
  • Pelvic Inflammatory Disease: 3 g IV every 6 hours
  • Surgical Prophylaxis(Preoperative dose): 3 g IV or IM once, starting within 60 minutes before surgical incision
  • Pediatric Bacterial Infection (1 year or older) >40 kg: 50 mg/kg (ampicillin component) IV every 6 hours <=40 kg: 1.5 to 3 g IV every 6 hours

These figures should not be considered in contravention of the advice of your medical professional and all current guidelines regarding additional treatment or conditions should be followed.

Major Drug Interactions

Some medications should not be used together because their mixture can cause undesirable and even deadly drug interactions. In some cases, this risk is necessary for the good of the patient when the potential effects are outweighed by the condition that is being treated. In cases of a major drug interaction, your doctor may change the dosage or take other precautions when administering these drugs in tandem. In other cases, substituting one or both of the medications may be necessary. It is imperative that your physician knows all medications that you are taking before administering an Ampicillin and Sulbactam injection for the treatment of infection. This is especially important in the event that you are taking any of the medications listed below. While this list is not comprehensive, the medications listed have had notable interactions with Ampicillin and Sulbactam treatment. While using this medicine with any of the following is not recommended, direct all questions regarding these potential interactions to your doctor at the time the treatment is prescribed.

  • Bupropion
  • Chlortetracycline
  • Cholera Vaccine, Live
  • Demeclocycline
  • Donepezil
  • Doxycycline
  • Lymecycline
  • Meclocycline
  • Methacycline
  • Minocycline
  • Oxytetracycline
  • Rolitetracycline
  • Tetracycline
  • Warfarin

Additionally, use of Khat, alcohol, or tobacco may cause adverse reactions when combined with an Ampicillin and Sulbactam regimen. Consuming certain foods or drink may also trigger an adverse reaction. Consult with your physician and let them know all vitamins or supplements that you are taking at the time of treatment.


Prior to beginning a course of treatment that includes Ampicillin and Sulbactam, your doctor should be made aware of your complete medical history including any past adverse reactions to medications. You will be closely supervised while receiving this medicine both because your physician needs to see how effective it is in treating your condition and to decide whether to continue the treatment. This may include periodic blood tests and other screenings to determine if any detrimental effects are happening as a result of the medication. Ampicillin and Sulbactam may cause serious allergic reactions for those that are susceptible, including life-threatening conditions such as anaphylaxis. Inform your doctor immediately if you experience the following symptoms:

  • Severe itching
  • Hives
  • Hoarseness
  • Difficulty breathing
  • Difficulty swallowing
  • Swelling of your hands, face, or mouth

This course of treatment can cause immediate diarrhea or it can be experienced up to 2 months after the treatment is over. If this is the case, do not take any medication for diarrhea without first checking with your doctor. These medications may cause a worsening of the condition or make it last longer than normal.

If you are undergoing any medical tests while being treated with Ampicillin and Sulbactam tell the administering physician that you are undergoing this treatment. Some test results may be affected by the medication. Use of Ampicillin and Sulbactam may decrease the effects of certain other medications. It has been documented that the effects of some oral contraceptives are decreased by this treatment. To avoid an unintended pregnancy, it is recommended that multiple birth control methods be used in addition to birth control pills when using this medicine. Do not take any medicines that have not been discussed with and approved by your doctor while you are being treated for infection. This includes not only prescription medications but also over-the-counter medications, herbal remedies, or vitamin supplements. Tell your doctor if you have a history of unusual or allergic reactions to any medication before beginning treatment and inform them of all known allergies.

Other medical conditions not related to infection may affect the use of Ampicillin and Sulbactam. Inform your doctor if you are currently experiencing any of the following medical conditions or symptoms as using this medication could make them worse:


This medication will be stored and maintained by the medical facility where you are seeking treatment and be handled only by medical professionals. It is to be stored in a controlled room temperature of 20° to 25°C (68° to 77°F) prior to reconstitution and can be transported briefly at between 15° and 30°C (59° and 86°F).


Ampicillin and sulbactam is a powerful antibiotic course of treatment that is packaged as a powder intended to be mixed with a liquid in order to be injected intravenously (into a vein) or intramuscularly (into a muscle) every 6 hours for the treatment of severe bacterial infections in various parts of the body. The length of treatment with Ampicillin and Sulbactam greatly depend on the type of infection that is being treated and how advanced the infection has become. The duration of treatment with an ampicillin and sulbactam injection can vary and your doctor will have more information on the length of treatment for your specific infection. As your condition improves you may need to continue treatment until the full course is completed or you may switch to an oral antibiotic to complete the treatment.

Whether you receive an ampicillin and sulbactam IV in a hospital or have it administered at home, you should do so under the direct supervision of a medical professional. If used at home, your healthcare provider should provide specific directions for how to use the medication. Ensure that you understand these directions and that all directions are followed. If you have any problems with using the medication at home ask your physician for help with infusing the medication intravenously.

Relief from the symptoms of a bacterial infection should be felt within a few days of initial treatment with Ampicillin and Sulbactam. If symptoms persist or worsen, you should inform your doctor immediately. If any indication of infection persists after the course of treatment concludes you should seek immediate medical attention. Use the injection until the prescription is concluded even if you feel better, as ceasing treatment early may give an infection an opportunity to rebound. If you stop using this treatment too soon your infection may return and become resistant to antibiotic treatment.

Last Reviewed:
December 24, 2017
Last Updated:
April 04, 2018
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