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Ampicillin, Oral Capsule

Highlights for ampicillin

  1. Ampicillin oral capsule is available as a generic drug only.
  2. Ampicillin also comes as an oral suspension as well as in an intravenous form, which is only given by a healthcare provider.
  3. Ampicillin is used to treat infections that are caused by a certain type of bacteria.
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Important warnings

Important warnings

  • Finish your full course of treatment: Finish all of your medication as prescribed by your doctor. Don’t stop taking your drug or skip doses if you start to feel better. Doing so could make your infection last longer. You could also become resistant to the drug. That means if you get another bacterial infection, ampicillin may not work to treat it.
  • Diarrhea: This drug may cause diarrhea. Call your doctor if you have bloody or watery diarrhea with or without stomach cramps and fever after you stop taking this drug.

About

What is ampicillin?

Ampicillin oral capsule is a prescription drug that’s only available in a generic form. It also comes as an oral suspension and in an intravenous (IV) form, which is only given by a healthcare provider.

Why it's used

Ampicillin is used to treat infections that are caused by a certain type of bacteria. Ampicillin may be used as part of a combination therapy. This means you may need to take it with other medications.

How it works

Ampicillin belongs to the drug class penicillin. A class of drugs is a group of medications that work in a similar way. These drugs are often used to treat similar conditions.

This drug works by killing bacteria to stop the infection from growing in your body.

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Side effects

Ampicillin side effects

Ampicillin oral capsule doesn’t cause drowsiness, but it can cause other side effects.

More common side effects

The more common side effects of ampicillin oral capsule can include:

  • nausea
  • vomiting
  • diarrhea
  • rash

If these effects are mild, they may go away within a few days or a couple of weeks. If they’re more severe or don’t go away, talk to your doctor or pharmacist.

Serious side effects

Call your doctor right away if you have serious side effects. Call 911 if your symptoms feel life-threatening or if you think you’re having a medical emergency. Serious side effects and their symptoms can include the following:

  • Allergic reactions. Symptoms can include:
    • flu-like symptoms, such as fever and body aches
    • painful red or purple rash that spreads
    • blisters that could lead to skin breakdown
  • Diarrhea that lasts after you stop taking the drug. Symptoms can include:
    • diarrhea with or without stomach cramps
    • diarrhea with a fever

Disclaimer: Our goal is to provide you with the most relevant and current information. However, because drugs affect each person differently, we cannot guarantee that this information includes all possible side effects. This information is not a substitute for medical advice. Always discuss possible side effects with a healthcare provider who knows your medical history.

Interactions

Ampicillin may interact with other medications

Ampicillin oral capsule can interact with other medications, vitamins, or herbs you may be taking. An interaction is when a substance changes the way a drug works. This can be harmful or prevent the drug from working well.

To help avoid interactions, your doctor should manage all of your medications carefully. Be sure to tell your doctor about all medications, vitamins, or herbs you’re taking. To find out how this drug might interact with something else you’re taking, talk to your doctor or pharmacist.

Examples of drugs that can cause interactions with ampicillin oral capsule are listed below.

Interactions that increase your risk of side effects

Increased side effects from ampicillin: Taking ampicillin with certain medications raises your risk of side effects from ampicillin. This is because the amount of ampicillin in your body may be increased. Examples of these drugs include:

  • Probenecid
    • Taking this drug with ampicillin can cause more side effects. These can include severe nausea, vomiting, and diarrhea.
  • Allopurinol
    • This drug increases the risk of skin rash when you take it with ampicillin.

Interactions that can make your drugs less effective

When ampicillin is less effective: When you take ampicillin with certain drugs, it may not work as well to treat your condition. This is because the amount of ampicillin in your body may be decreased. Examples of these drugs include:

  • Antibiotics such as chloramphenicol, macrolides, sulfonamides, and tetracyclines
    • Your doctor may increase your ampicillin dosage or decrease the dosage of your other antibiotic if you need to take them together.

When other drugs are less effective: When certain drugs are used with ampicillin, they may not work as well. This is because the amount of these drugs in your body may be decreased. Examples include:

  • Oral contraceptives (birth control pills)
    • Your doctor may prescribe a different form of birth control for you.

Disclaimer: Our goal is to provide you with the most relevant and current information. However, because drugs interact differently in each person, we cannot guarantee that this information includes all possible interactions. This information is not a substitute for medical advice. Always speak with your healthcare provider about possible interactions with all prescription drugs, vitamins, herbs and supplements, and over-the-counter drugs that you are taking.

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Other warnings

Ampicillin warnings

This drug comes with several warnings.

Allergies

Ampicillin can cause a severe allergic reaction. Symptoms can include:

  • rash
  • trouble breathing
  • swelling of your throat or tongue

If you have an allergic reaction, call your doctor or local poison control center right away. If your symptoms are severe, call 911 or go to the nearest emergency room. Do not take this drug again if you’ve ever had an allergic reaction to it. Taking it again could be fatal.

Warnings for people with certain health conditions

For people with gonorrhea and syphilis: This drug alone won’t treat syphilis. You must receive an injectable dose of penicillin if you have gonorrhea and syphilis.

For people with diabetes: This drug may cause a false positive when your doctor tests you for glucose (sugar) in your urine. That means the test may say you have glucose in your urine when you really don’t. Ask your doctor if this drug is safe for you.

For people with kidney problems: If you have kidney problems or a history of kidney disease, you may not be able to clear this drug from your body well. This may increase the levels of drug in your body and cause more side effects.

Warnings for other groups

For pregnant women: Ampicillin is a category B pregnancy drug. That means two things:

  1. Research in animals has not shown a risk to the fetus when the mother takes the drug.
  2. There aren’t enough studies done in humans to show if the drug poses a risk to the fetus.

Talk to your doctor if you’re pregnant or planning to become pregnant. Animal studies do not always predict the way humans would respond. Therefore, this drug should only be used in pregnancy if clearly needed.

Call your doctor right away if you become pregnant while taking this drug.

For women who are breastfeeding: Ampicillin may pass into breast milk and cause side effects in a child who is breastfed. Talk to your doctor if you breastfeed your child. You may need to decide whether to stop breastfeeding or stop taking this medication.

For seniors: The kidneys of older adults may not work as well as they used to. This can cause your body to process drugs more slowly. As a result, more of a drug stays in your body for a longer time. This raises your risk of side effects.

For children: Newborns and infants should take the lowest dosage of this drug possible. This is because their kidneys aren’t fully developed. It may take longer for this drug to be removed from their bodies. This means it can cause more side effects.

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Dosage

How to take ampicillin

This dosage information is for ampicillin oral capsule. All possible dosages and drug forms may not be included here. Your dosage, drug form, and how often you take the drug will depend on:

  • your age
  • the condition being treated
  • how severe your condition is
  • other medical conditions you have
  • how you react to the first dose

The dosage information below is for the conditions that this drug is most often prescribed to treat. This list may not contain all conditions that your doctor can prescribe this drug for. If you have questions about your prescription, talk with your doctor.

Forms and strengths

Generic: Ampicillin

  • Form: oral capsule
  • Strengths: 250 mg, 500 mg

Dosage for genitourinary tract infections, gonorrhea

Adult dosage (ages 18–64 years)

For genitourinary tract infections other than gonorrhea:

  • Typical dosage is 500 mg four times per day.

For gonorrhea:

  • Typical dosage is 3.5 grams as a single dose.

Child dosage (children who weigh 20kg or more)

For genitourinary tract infections other than gonorrhea:

  • Typical dosage is 500 mg four times per day.

For gonorrhea:

  • Typical dosage is 3.5 grams as a single dose.

Child dosage (children who weigh less than 20kg)

For genitourinary tract infections:

  • Typical dosage is 100 mg/kg per day in four equally divided and spaced doses.

Senior dosage (ages 65 years and older)

The kidneys of older adults may not work as well as they used to. This can cause your body to process drugs more slowly. As a result, more of a drug stays in your body for a longer time. This raises your risk of side effects.

Your doctor may start you on a lowered dosage or a different schedule. This can help keep levels of this drug from building up too much in your body.

Dosage for respiratory tract infections

Adult dosage (ages 18–64 years)

  • Typical dosage is 250 mg four times per day.

Child dosage (children who weigh 20kg or more)

  • Typical dosage is 250 mg four times per day.

Child dosage (children who weigh less than 20kg)

  • Typical dosage is 50 mg/kg per day in equally divided and spaced doses three to four times per day.

Senior dosage (ages 65 years and older)

The kidneys of older adults may not work as well as they used to. This can cause your body to process drugs more slowly. As a result, more of a drug stays in your body for a longer time. This raises your risk of side effects.

Your doctor may start you on a lowered dosage or a different schedule. This can help keep levels of this drug from building up too much in your body.

Dosage for gastrointestinal tract infections

Adult dosage (ages 18–64 years)

  • Typical dosage is 500 mg four times per day.

Child dosage (children who weigh 20kg or more)

  • Typical dosage is 500 mg four times per day.

Child dosage (children who weigh less than 20kg)

  • Typical dosage is 100 mg/kg per day in four equally divided and spaced doses.

Senior dosage (ages 65 years and older)

The kidneys of older adults may not work as well as they used to. This can cause your body to process drugs more slowly. As a result, more of a drug stays in your body for a longer time. This raises your risk of side effects.

Your doctor may start you on a lowered dosage or a different schedule. This can help keep levels of this drug from building up too much in your body.

Dosage for meningitis

Adult dosage (ages 18–64 years)

Your doctor will decide the dosage that’s right for you.

Child dosage (ages 0–17 years)

Your child’s doctor will decide the dosage that’s right for your child.

Senior dosage (ages 65 years and older)

The kidneys of older adults may not work as well as they used to. This can cause your body to process drugs more slowly. As a result, more of a drug stays in your body for a longer time. This raises your risk of side effects.

Your doctor may start you on a lowered dosage or a different schedule. This can help keep levels of this drug from building up too much in your body.

Disclaimer: Our goal is to provide you with the most relevant and current information. However, because drugs affect each person differently, we cannot guarantee that this list includes all possible dosages. This information is not a substitute for medical advice. Always to speak with your doctor or pharmacist about dosages that are right for you.

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Take as directed

Take as directed

Ampicillin oral capsule is used for short-term treatment. It comes with serious risks if you don’t take it as prescribed.

If you stop taking the drug suddenly or don’t take it at all: Your bacterial infection may not get better. It may even get worse.

If you miss doses or don’t take the drug on schedule: Your medication may not work as well or may stop working completely. For this drug to work well, a certain amount needs to be in your body at all times.

Finish all of your medication that your doctor prescribes. Don’t stop taking your drug or skip doses if you start to feel better. Doing so could make your infection last longer. You could also become resistant to the drug. This means that if you get another bacterial infection, ampicillin may not work to treat it.

If you take too much: You could have dangerous levels of the drug in your body. Symptoms of an overdose of this drug can include upset stomach and diarrhea.

If you think you’ve taken too much of this drug, call your doctor or local poison control center. If your symptoms are severe, call 911 or go to the nearest emergency room right away.

What to do if you miss a dose: Take your dose as soon as you remember. But if you remember just a few hours before your next scheduled dose, take only one dose. Never try to catch up by taking two doses at once. This could result in dangerous side effects.

How to tell if the drug is working: The symptoms of your infection will get better.

Important considerations

Important considerations for taking ampicillin

Keep these considerations in mind if your doctor prescribes ampicillin oral capsule for you.

General

  • Don’t take this drug with food.
  • Take this drug with 8 oz. of water 30 minutes before eating or two hours after eating.

Storage

  • Store the capsules at room temperature between 68°F and 77°F (20°C and 25°C).
  • Store them away from light.

Refills

A prescription for this medication is refillable. You should not need a new prescription to refill this medication. Your doctor will write the number of refills authorized on your prescription.

Travel

When traveling with your medication:

  • Always carry your medication with you. When flying, never put it into a checked bag. Keep it in your carry-on bag.
  • Don’t worry about airport x-ray machines. They can’t hurt your medication.
  • You may need to show airport staff the pharmacy label for your medication. Always carry the original prescription-labeled box with you.
  • Don’t put this medication in your car’s glove compartment or leave it in the car. Be sure to avoid doing this when the weather is very hot or very cold.

Clinical monitoring

Your doctor will likely monitor certain health issues during your treatment. This can help make sure you stay safe while you take this drug. These issues include:

  • Kidney function. Your doctor may do blood tests to check how well your kidneys are working. If your kidneys don’t work well, your doctor may reduce how often you take this drug.
  • Liver function. Your doctor may do blood tests to check how well your liver is working. If your liver doesn’t work well, your doctor may lower your dosage of this drug.
  • Blood cell counts. Your doctor may do blood tests to check if this drug is reducing your red blood cell and platelet levels. If it is, your doctor may lower your dosage or your stop treatment with the drug.
  • Syphilis. If you have gonorrhea, your doctor will also test for you for syphilis. They’ll do this when you start the drug and then again three months later. This is because treatment for gonorrhea can mask symptoms of syphilis.
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Alternatives

Are there any alternatives?

There are other drugs available to treat your condition. Some may be better suited for you than others. Talk to your doctor about other drug options that may work for you.

Disclaimer: Healthline has made every effort to make certain that all information is factually correct, comprehensive, and up-to-date. However, this article should not be used as a substitute for the knowledge and expertise of a licensed healthcare professional. You should always consult your doctor or other healthcare professional before taking any medication. The drug information contained herein is subject to change and is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. The absence of warnings or other information for a given drug does not indicate that the drug or drug combination is safe, effective, or appropriate for all patients or all specific uses.

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