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How to Take Ampicillin - Uses, Dosage and Side Effects

Max. D Gray
By Max. D Gray. Updated: January 16, 2017
How to Take Ampicillin - Uses, Dosage and Side Effects

Ampicillin is an antibiotic derived from penicillin which is widely used to treat bacterial infections. At OneHowTo.com, we will explain how to take ampicillin, what it is used for, its possible side effects, pharmacological forms, dosage and any precautions you should take.

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  1. Uses of ampicillin
  2. How to take ampicillin
  3. Precautions
  4. Side effects
  5. Pregnancy and lactation
  6. Excipients

Uses of ampicillin

Ampicillin is used to treat a number of bacterial infections which are sensitive to this antibiotic, such as:

  • Bacterial Meningitis. Ampicillin is effective against most of the pathogens which cause this disease.
  • Genito-urinary tract infections including gonorrhea.
  • Upper respiratory and ENT tract infections: Bacterial pharyngitis, sinusitis and ear infection.
  • Lower respiratory tract infections: Pneumonia and bronchitis which were not transmitted within a hospital setting.
  • Gastrointestinal tract infections: salmonella
  • Skin and soft tissues infections.
  • Neonatal infections
  • Odontostomatological infections, caused by surgery, sepsis, bacterial endocarditis or typhoid amongst others.

How to take ampicillin

Ampicillin should be administered orally in:

  • Children: Up to 14 years of age the recommended dose is 100-200 mg / kg every 6 hours for at least 7 days.
  • Adults: 500 mg to 1 g per oral route every 6 hours for 7 to 10 days depending on the type of infection and the severity of the disease.

IV administration:

  • Adults and children weighing more than 20 kg:

The usual dose is 500 mg intravenously or intramuscularly every 6 hours. Higher doses may be required for severe or chronic infections not exceeding 14 grams a day.

  • Children weighing less than 20 kg:

The usual dose is 100 mg / kg / day in total, administered every 6 hours.

  • Neonates: intravenous or intramuscular. Doses of 25-50 mg / kg / dose. The frequency of administration can be adjusted depending on the gestational age of the patient.

Since fasting improves the absorption of ampicillin, and therefore its effects, it should be administered at least half an hour before or two hours after eating.

Treatment should be continued for as long as the doctor has indicated and should never be stopped beforehand, even if the symptoms have disappeared.

Ampicillin comes in capsules, as a liquid solution and pediatric drops to be taken orally. The pediatric drops and liquid solution should be shaken well before each use to mix the medication evenly. You should use the dropper that comes with the package to measure the dose of the pediatric drops. The drops and the liquid may be placed on the child's tongue or added to breast milk, milk, fruit juice, water or other cold liquids and taken immediately. The capsules should be swallowed whole and not chewed accompanied by a large glass of water.

With the IV forms of administration, the powder should be mixed with the contents of the blister (water for injection). Once prepared, administer immediately as its period of stability is very short. When used intravenously, ampicillin is compatible with most commonly used fluids: saline, Dextrose 5% or 10% but should never be mixed with blood, plasma, protein hydrolysates, amino acid solutions or with lipid emulsions. Ampicillin is incompatible with solutions containing aminoglycosides, metronidazole, amphotericin B, heparin and cortisol.

If you miss an injection, you should take the missed dose as soon as you remember, however, if it is already time for the next dose, you should skip the missed injection and continue with your regular dosing schedule. Never take a double dose to compensate for a missed dose.

It must be preserved at room temperature not exceeding 30°C (86 °F) and in a dry place. It should never be frozen.


It is recommended to reserve the intravenous or intramuscular administration of ampicillin for moderately severe to severe infections and for patients who cannot take the medication orally, either as capsules or as syrups.

This medication is not recommended in patients suffering from infectious mononucleosis, or other viral infections, due to the risk of drug irrigation eruption, also called rash. Although generally well tolerated with a low level of toxicity, it is advisable that, during prolonged treatments, the correct renal, hepatic and hematopoietic functions of the body are evaluated periodically.

The prescription of ampicillin in the absence of a bacterial infection is unlikely to benefit the patient and increases the risk of developing bacteria resistant to the medication.

Ampicillin should be administered with caution to patients with renal failure, adjusting the dosage and frequency according to the severity of the damage.

If you experience diarrhea after starting taking this medication, you should contact your doctor as soon as possible. The same applies to vaginal thrush.

You should contact your doctor if you are taking any of these medicines as they may react with ampicillin:

Allopurinol: greater chance of rash, particularly in people with high uric acid levels.

Bacteriostatic antibiotics: Chloramphenicol, erythromycin, sulfonamides and tetracyclines may interfere with the effects of ampicillin.

Oral contraceptives: These may become less effective and present intermittent bleeding.

Probenecid and Disulfiram: These can increase blood levels of ampicillin and cause toxicity.

Side effects

Gastrointestinal: The side effects of ampicillin are similar to those of other antibiotics and are due to reduction of intestinal flora: Nausea, vomiting, anorexia (lack of appetite), diarrhea, gastritis, abdominal pain and enterocolitis. These reactions are usually associated with oral doses of ampicillin.

Hypersensitivity reactions: Erythematous rash occurs very frequently, with medium intensity itching. The rash can cover the entire body, soles, palms and oral mucosa. It usually disappears within a period of three to seven days.

Other hypersensitivity reactions: Pruritus, urticaria, erythema multiforme and occasional cases of exfoliative dermatitis. Anaphylaxis is the most serious reaction that may be experienced. This is associated with IV doses of ampicillin. In this case a difficulty arises in breathing, swallowing and loss of consciousness.

If any of these reactions occur whilst using ampicillin, treatment should be discontinued unless, in a doctor's professional opinion, the condition being treated endangers the patient's life and can only be treated with this antibiotic.

Liver: There has been a slight increase in levels of serum glutamic oxaloacetic transaminase (SGOT).

Hemic and Lymphatic System: Anemia, thrombocytopenia, thrombotic thrombocytopenic purpura, eosinophilia, leukopenia and agranulocytosis have all been reported during treatment with ampicillin.

These reactions are usually reversible upon discontinuation of treatment.

Prolonged use of antibiotics may promote the proliferation of fungi. If an infection occurs, take the appropriate treatment.

Central Nervous System: Headache, restlessness, insomnia, and confusion, although not very frequent.

Pregnancy and lactation

Ampicillin should only be used during pregnancy when clearly necessary as there are no adequate and well controlled studies in pregnant women.

Ampicillin is excreted in breast milk so can lead to the sensitization of the baby to this antibiotic, diarrhea and rashes. Therefore, the physician must decide whether to discontinue breastfeeding or the use of ampicillin, considering the importance of the drug to the mother.


The excipients are preservatives and other products that make up the drug. These will differ depending on the pharmaceutical form and they should be avoided if you are allergic to them:

  • Oral Form: Sucrose, sodium benzoate.
  • The sodium content in the injection is 2.9mEq / gram of ampicillin.

This article is merely informative, oneHOWTO does not have the authority to prescribe any medical treatments or create a diagnosis. We invite you to visit your doctor if you have any type of condition or pain.

If you want to read similar articles to How to Take Ampicillin - Uses, Dosage and Side Effects, we recommend you visit our Drugs & supplements category.

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How to Take Ampicillin - Uses, Dosage and Side Effects