Ampicillin : Uses, Side Effects, Interactions & More
Why is this medication prescribed?
Ampicillin is used to treat certain infections caused by bacteria such as meningitis (infection of the membranes that surround the brain and spinal cord); and infections of the throat, sinuses, lungs, reproductive organs, urinary tract, and gastrointestinal tract. Ampicillin belongs to a class of medications called penicillins. It works by killing bacteria.
Antibiotics like ampicillin don’t work for colds, flu, or other viral infections. Taking antibiotics when they are not needed increases the risk of getting an infection later that resists antibiotic treatment.
How should this medicine be used?
Ampicillin comes as a capsule and a suspension (liquid) to take by mouth. It is usually taken three to four times a day, either half an hour before or two hours after meals. The length of your treatment depends on the type of infection you have. Take ampicillin at around the same times every day. Follow the directions on your prescription label carefully and ask your doctor or pharmacist to explain any parts you do not understand. Take ampicillin exactly as directed. Do not take more or less, or take it more often than prescribed by your doctor.
Shake the suspension well before each use to mix the medicine evenly.
The medicine should be taken with a full glass of water.
You should start to feel better during the first few days of treatment with ampicillin. If your symptoms don’t improve or get worse, call your doctor.
Take ampicillin until the prescription is finished, even if you feel better. If you stop taking ampicillin too soon or miss doses, your infection may not be fully treated and the bacteria may become resistant to antibiotics.
Other uses for this medicine
This medication may be prescribed for other uses; ask your doctor or pharmacist for more information.
What special precautions should I follow?
Before taking ampicillin,
- Tell your doctor and pharmacist if you are allergic to ampicillin; penicillins; Cephalosporin antibiotics such as Cefaclor, Cefadroxil, Cefazolin (Ancef, Kefzol), Cefdinir, Cefditoren, Cefepime (Maxipime), Cefixime (Suprax), Cefotaxime (Claforan), Cefotetan, Cefoxitin (Mefoxin, Kefzol), Tazimezidime Cefpoftazime (Ceftazime) in Avycaz), ceftibuten, ceftriaxone, cefuroxime (Ceftin, Zinacef) and cephalexin (Keflex); any other medication; or any of the ingredients in ampicillin capsules or suspension. Ask your pharmacist for a list of the ingredients.
- Tell your doctor and pharmacist what other prescription and nonprescription medications, vitamins, nutritional supplements, and herbal products you are taking or plan to take. Be sure to mention any of the following: allopurinol (Lopurin, Zyloprim), other antibiotics, oral contraceptives, and probenecid (Probalan in Col-Probenecid,). Your doctor may need to change the doses of your medications or monitor you closely for side effects.
- Tell your doctor if you have mononucleosis (a virus also called ‘mono’) and if you have or have ever had allergies, asthma, hives, hay fever, or kidney disease.
- Tell your doctor if you are pregnant, plan to become pregnant, or are breastfeeding. If you become pregnant while taking ampicillin, call your doctor.
What special dietary instructions should I follow?
Unless your doctor tells you otherwise, continue your normal diet.
What should I do if I forget a dose?
Take the missed dose as soon as you remember. However, if it is almost time for the next dose, skip the missed dose and continue your regular dosing schedule. Do not take a double dose to make up for the one you forgot.
What side effects can this medication cause?
Ampicillin may cause side effects. Tell your doctor if any of these symptoms are severe or do not go away:
- diarrhea
- nausea
- vomiting
Some side effects can be serious. If you experience any of the following symptoms, stop taking ampicillin and call your doctor immediately or get emergency medical treatment:
- rash
- itching
- hives
- difficulty breathing or swallowing
- wheezing
- severe diarrhea (watery or bloody stools) that may occur with or without fever and stomach cramps (may occur up to 2 months or more after your treatment)
- a return of fever, cough, sore throat, chills, and other signs of infection
If you experience a serious side effect, you or your doctor can submit a report online to the Food and Drug Administration’s (FDA) MedWatch Adverse Event Reporting program (http://www.fda.gov/Safety/MedWatch) or by phone (1-800-332-1088).
What should I know about storage and disposal of this medication?
Keep this medicine in the container it came in, tightly closed, and out of the reach of children. Store the capsules at room temperature and away from excess heat and moisture (not in the bathroom). Keep the suspension in the refrigerator, tightly closed, and discard the unused suspension after 14 days. Do not freeze.
Unnecessary medications must be disposed of in special ways to ensure they cannot be consumed by pets, children, and others. However, you should not flush this medicine down the toilet. Instead, the best way to dispose of your medications is through a drug take-back program. Talk to your pharmacist or contact your local garbage / recycling department to find out about take-back programs in your community. See the FDA Safe Drug Disposal website (http://goo.gl/c4Rm4p) for more information if you do not have access to a take-back program.
It is important to keep all medicines out of the sight and reach of children, since many containers (such as those containing weekly pills and those for eye drops, creams, patches and inhalers) are not resistant to children and small children can easily open them. To protect young children from poisoning, always close the safety caps and immediately place the medicine in a safe place, one that is upright and out of their sight and reach. http://www.upandaway.org
In case of emergency/overdose
In case of overdose, call the poison control helpline at 1-800-222-1222. Information is also available online at https://www.poisonhelp.org/help. If the victim collapsed, had a seizure, has trouble breathing, or cannot wake up, immediately call 911 for emergency services.
What other information should I know?
Keep all appointments with your doctor and the laboratory. Your doctor may order certain lab tests to check your response to ampicillin.
If you are diabetic and your urine is tested for sugar, use Clinistix or TesTape (not Clinitest) to test your urine while taking this drug.
Do not let anyone else take your medicine. Your prescription may not be refilled. If you still have symptoms of infection after you finish ampicillin, call your doctor.
It is important that you keep a written list of all prescription and over-the-counter (over-the-counter) medications you are taking, as well as any products such as vitamins, minerals, or other dietary supplements. You should take this list with you each time you visit a doctor or if you go into hospital. It is also important information to take with you in case of emergencies.
Brand Names
- Amcill®
- Omnipen®
- Penbritin®
- Pfizerpen®
- Polycillin®
- Principen®
- Totacillin®
Other Names
- Aminobenzylpenicillin
Disclaimer: We have made every effort to ensure that all information is factually accurate, comprehensive and up-to-date. However, this article should not be used as a licensed health care professional’s choice of knowledge and expertise. You should always consult your doctor or other health care professional before taking any medication. The information given here is subject to change and it has not been used to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions or adverse effects. The lack of warning or other information for any drug does not indicate that the combination of medicine or medication is safe, effective or appropriate for all patients or all specific uses.