Erythromycin, oral

Generic Name: Erythromycin

  • What is Erythromycin, oral?

    Erythromycin is an antibiotic used to treat many kinds of infections, including acute pelvic inflammatory disease, chlamydia, gonorrhea, intestinal parasitic infections, Legionnaires' disease, listeriosis, conjunctivitis ("pink-eye"), rectal infections, reproductive tract infections, skin infections, syphilis, upper and lower respiratory tract infections, urinary tract infections, and whooping cough.

    Erythromycin is also prescribed to prevent rheumatic fever in people who are allergic to penicillin and sulfa drugs. It is prescribed before colorectal surgery to prevent infection.

  • What is the most important information I should know about Erythromycin, oral?

    Antibacterial drugs, including Erythromycin, should only be used to treat bacterial infections. They do not treat viral infections, such as the common cold or flu. Although it is common to feel better soon after you start therapy, take the full course of the drug exactly as directed. Skipping doses or not completing the full course of therapy may decrease the effectiveness of the immediate treatment and increase the likelihood that bacteria will develop resistance and will not be treatable by Erythromycin or other antibacterial drugs in the future.

    Diarrhea is a common problem caused by antibiotics and usually ends when the antibiotic is discontinued. Sometimes after starting treatment with antibiotics, people can develop watery and bloody stools (with or without stomach cramps and fever) even as late as 2 or more months after having taken the last dose of the antibiotic. If this occurs, you should contact your physician as soon as possible.

  • Who should not take Erythromycin, oral?

    Do not use Erythromycin if you have previously had an allergic reaction to it or are sensitive to this medication.

    You should not take Erythromycin if you are currently taking terfenadine, astemizole, pimozide, or cisapride.

  • What should I tell my doctor before I take the first dose of Erythromycin, oral?

    Tell your doctor about all prescription, over-the-counter, and herbal medications you are taking before beginning treatment with this drug. Also, talk to your doctor about your complete medical history, especially if you have ever had liver or kidney disease, heart problems, a fast or irregular heartbeat, or if you have myasthenia gravis (a type of muscle weakness). Also, tell your doctor if you are pregnant, plan to become pregnant, or are breastfeeding.

  • What is the usual dosage?

    The information below is based on the dosage guidelines your doctor uses. Depending on your condition and medical history, your doctor may prescribe a different regimen. Do not change the dosage or stop taking your medication without your doctor's approval.

    Dosage instructions are determined by the type and severity of infection being treated and may vary. General dosages are listed immediately below.

    Adults: The usual dosage is one 250-milligram (mg) tablet four times daily in equally spaced doses or one 500-mg tablet every 12 hours. Dosage may be increased up to 4 grams (g) per day based on the severity of the infection.

    Children: Age, weight, and severity of the infection determine the correct dosage. The usual dosage is from 30-50 mg daily per 2.2 pounds of body weight, divided into equal doses. For more severe infections, the dosage may be doubled but should not exceed 4 g per day.

    Acute Pelvic Inflammatory Disease

    Adults: The usual treatment is 3 days of intravenous (in the vein) Erythromycin followed by 500 mg by mouth given every 12 hours for 7 days.

    Conjunctivitis (Pink Eye)

    Newborns: The dosage is 50 mg per 2.2 pounds of body weight per day given in four divided doses for at least 2 weeks, given as a liquid.

    Intestinal Infections

    Adults: 500 mg given every 12 hours or 250 mg given every 6 hours for 10-14 days.

    Children: 30-50 mg per 2.2 pounds of body weight per day given in divided doses for 10-14 days.

    Legionnaires' Disease

    Adults: The usual dosage ranges from 1-4 grams (g) daily, divided into smaller doses. No optimal dose has been established.


    Infants: The recommended dose is 50 mg per 2.2 pounds of body weight per day given in 4 divided doses for at least 3 weeks, given as a liquid.

    Rheumatic Fever Prevention

    People allergic to penicillin and sulfonamides: 250 mg given twice a day.


    Adults: The usual dosage is 30-40 g given in divided doses over a period of 10-15 days.

    Uncomplicated Urinary, Reproductive Tract, or Rectal Infections

    For adults who cannot take tetracycline: The usual dosage is 500 mg given four times a day for at least 7 days.

    Upper Respiratory Tract Infections

    Adults and Children: Your doctor will determine the correct dose based on the infection.

    Urethral Infections

    For adults who cannot take tetracycline: The usual dosage is 500 mg given four times a day for at least 7 days.

    Urinary Tract Infections During Pregnancy

    Adults: The usual dosage is 500 mg given on an empty stomach four times a day for at least 7 days. For women who cannot tolerate this regimen, a decreased dose 500 mg given every 12 hours or 250 mg given four times a day for at least 14 days.

    Whooping Cough

    Children: Although an optimal dose and duration of therapy have not been established, a daily dose of 40-50 mg per 2.2 pounds of body weight given in divided doses for 5-14 days has been utilized in clinical trials.

  • How should I take Erythromycin, oral?

    Some forms of Erythromycin are most effective when taken on an empty stomach. Your doctor may advise you to take each dose at least 1/2 hour and preferably 2 hours before meals.

    Delayed-release formulations may be taken with or without food. If the drug upsets your stomach, taking it with meals may help. Delayed-release tablets and capsules that are coated to slow their breakdown should be swallowed whole. Do not crush or break. If you are not sure about the form of Erythromycin you are taking, ask your pharmacist.

    Chewable forms of Erythromycin should be crushed or chewed before being swallowed.

    The liquid should be shaken well before each use.

    To clear up your infection completely, take Erythromycin for the full course of treatment, even if you feel better in a few days.

  • What should I avoid while taking Erythromycin, oral?

    Avoid prolonged or repeated use of Erythromycin, since this may result in the growth of bacteria or fungi that do not respond to this medication and can cause a secondary infection.

    Do not eat grapefruit or drink grapefruit juice while you use Erythromycin.

  • What are possible food and drug interactions associated with Erythromycin, oral?

    Combining Erythromycin with lovastatin can cause severe muscle wasting and damage to the kidneys. If you are taking both of these drugs, your doctor will monitor you closely for warning signs of this interaction.

    If Erythromycin is taken with certain other drugs, the effects of either could be increased, decreased, or altered. It is especially important to check with your doctor before combining erythromycin with the following: alfentanil, benzodiazepines, blood-thinners, bromocriptine, carbamazepine, cilostazol, cyclosporine, digoxin, dihydroergotamine, disopyramide, ergotamine, hexobarbital, lovastatin, methylprednisolone, quinidine, rifabutin, seizure medications, sildenafil, simvastatin, tacrolimus, theophylline, or vinblastine.

  • What are the possible side effects of Erythromycin, oral?

    Side effects cannot be anticipated. If any develop or change in intensity, tell your doctor as soon as possible. Only your doctor can determine if it is safe for you to continue taking this drug.

    Side effects may include: stomach pain, diarrhea, loss of appetite, nausea, vomiting, bloody stools, hearing changes, irregular heartbeat, red, swollen, or blistered skin, yellowing of skin or eyes

  • Can I receive Erythromycin, oral if I am pregnant or breastfeeding?

    There is no evidence that Erythromycin will harm a developing baby, but the possibility has not been completely ruled out. If you are pregnant or plan to become pregnant, inform your doctor immediately. Erythromycin appears in breast milk and could affect a nursing infant. Consult your doctor before breastfeeding.

  • What should I do if I miss a dose of Erythromycin, oral?

    If you miss a dose of Erythromycin, take it as soon as possible. If it is almost time for the next dose, skip the missed dose and go back to your regular dosing schedule. Do not take two doses at once.

  • How should I store Erythromycin, oral?

    Store at room temperature away from heat, moisture, and light. Do not store in the bathroom. The liquid form of Erythromycin should be kept in the refrigerator; do not freeze. Keep tightly closed.

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