Erythromycin dosage, forms, and strengths

Erythromycin is a generic prescription antibiotic commonly used to treat bacterial infections and some parasite infections. Tablets are the most common dosage format, but some conditions may require injections. Erythromycin is also a commonly prescribed topical drug used to treat acne or eye infections. Erythromycin, belonging to a class of antibiotics called macrolide antibiotics, blocks the ability of bacteria to synthesize the proteins they need to survive. 

Erythromycin forms and strengths

Erythromycin has many uses and many dosage formats. These include:

• Tablets: 250 milligrams (mg), 400 mg, 500 mg

• Delayed-release tablets: 250 mg, 333 mg, 500 mg

• Delayed-release capsules: 250 mg

• Oral suspension: 200 mg/5 milliliters (mL)

• Gel (acne): 2%

• Solution (acne): 2%

• Pads (acne): 2%

• Ophthalmic ointment: 0.5% (5 mg per gram)

• Injections: 500 mg per vial (doses will vary)

Erythromycin dosage for adults

As an antibiotic, erythromycin is primarily used to treat bacterial infections. Other uses approved by the Food and Drug Administration (FDA) include rheumatic fever prophylaxis and amoeba infections, off-label uses for some infections, and even non-infections such as delayed stomach emptying (gastroparesis). Though it has been approved for a variety of infections, for many of these conditions, erythromycin is not the preferred treatment.

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Erythromycin dosage for bacterial infections

The FDA approves Erythromycin for the treatment of many bacterial infections, including upper respiratory tract infections, lower respiratory tract infections (Streptococcus or Mycoplasma pneumonia), listeriosis (Listeria infection), skin infections, soft tissue infections, and erythrasma. All of these are treated with the same standard daily dosage. However, treatment durations may vary based on the infection and its severity.

• Standard erythromycin dosage for bacterial infections: 250 mg taken four times per day or 500 mg taken twice per day

• Maximum erythromycin dosage for bacterial infections: 1 g taken four times per day or 2 g taken twice per day

Erythromycin dosage for acne

Erythromycin is a standard topical antibiotic treatment for acne. It is frequently combined with benzoyl peroxide, which fights bacteria and reduces swelling. The duration of treatment will vary, but people will apply erythromycin gel or topical solution to the affected skin twice daily.

• Standard erythromycin dosage for acne: Apply to the affected skin twice per day, once in the morning and once in the evening

Erythromycin dosage for eye infections

Topical erythromycin has received FDA approval for treating bacterial infections affecting the eye's surface. A small ribbon about one centimeter long is squeezed onto the inner edge of the lower eyelid several times daily. The number of doses per day and the duration of treatment will depend on the severity of the infection.

• Standard erythromycin dosage for superficial bacterial eye infections: One cm ribbon of ointment applied to the eye up to six times per day 

Erythromycin dosage for pertussis

Bordetella pertussis, or whooping cough, is usually a childhood bacterial respiratory infection. It can occur in unvaccinated adults or who haven’t been previously infected. Erythromycin is the preferred treatment, but it does little to change the course or severity of the infection if it’s started after symptoms appear. Instead, it helps reduce the risk of spreading the infection. Postexposure prophylaxis with erythromycin is also recommended for all close contacts to an individual diagnosed with pertussis.

• Standard erythromycin dosage for whooping cough: 500 mg taken orally four times per day for 14 days

Erythromycin dosage for diphtheria

The standard treatment for diphtheria is diphtheria antitoxins and an antibiotic. The first-line antibiotic treatments are erythromycin or penicillin.

• Standard erythromycin dosage for diphtheria: 40–50 mg/kg daily divided into two or four doses for 14 days

Erythromycin dosage for rheumatic fever prevention

Acute rheumatic fever is an abnormal immune response by the body to strep infections. For most people, it first occurs in childhood. Rheumatic fever affects many organs and can damage those organs. Worse still, once it happens, it often recurs, causing more organ damage. Repeated bouts of rheumatic fever can cause severe heart disease, so preventing rheumatic fever usually involves years or decades of antibiotic treatment. The preferred treatment is penicillin, but erythromycin may be used in people with penicillin allergies.

• Standard erythromycin dosage for rheumatic fever prophylaxis: 250 mg taken orally every 12 hours for five years or until age 21, whichever is longer (for people with no heart effects) or 10 years or until age 21, whichever is longer (for people whose hearts have been affected) or 10 years or until age 40 whichever is longer (for people whose hearts have been affected and have residual heart disease) 

Erythromycin dosage for other FDA-approved indications

Despite erythromycin having FDA approval for many other infections, it’s usually not prescribed.

• For urinary tract chlamydia infections or urethral infections caused by Ureaplasma bacteria, tetracycline antibiotics are the preferred treatment. Erythromycin is not part of the treatment guidelines but may be used in people who can’t take tetracyclines.

• Pelvic inflammatory disease is a serious infection of the upper genital and urinary tract that is usually caused by sexually transmitted infections (STIs). Erythromycin is FDA approved to treat PID due to gonorrhea but is not included in recommended treatment guidelines.

• Legionnaire’s disease is a life-threatening respiratory tract infection. Treatment guidelines give doctors a choice of prescribing a macrolide antibiotic, but the preferred macrolide is azithromycin. 

• Intestinal amebiasis or amoebic dysentery is a severe diarrheal disease caused by a parasite infestation of the colon. Although erythromycin has received FDA approval to treat amoebic dysentery in adults, the antibiotics metronidazole or tinidazole are the recommended treatments. 

• Syphilis is a common STI normally treated with penicillin or tetracyclines. While erythromycin has FDA approval for addressing primary or first-stage syphilis, it is not advisable for treatment due to the potential for drug resistance. 

Erythromycin dosage for children

Erythromycin is used in children to treat many of the same bacterial infections as adults. Doses are usually based on body weight, but the number of doses per day and the duration of treatment is the same as in adults. Although topical erythromycin is commonly prescribed to adolescents with acne, this is not an FDA-approved use. 

• Standard erythromycin dosage for bacterial infections in infants and children: 30–50 mg/kg per day taken every six to eight hours

• Maximum erythromycin dosage for bacterial infections in infants and children: 2 to 4 grams per day

• Standard erythromycin adolescent dosage for acne: Same as adult dosage

• Standard erythromycin pediatric dosage for superficial bacterial eye infections: One cm ribbon of ointment applied to the eye up to six times per day for seven to 10 days 

• Standard erythromycin neonatal dosage to prevent chlamydia conjunctivitis: 50 mg/kg/day taken every six hours for at least two weeks OR 1 cm ribbon applied to the conjunctival sac up to six times daily 

• Standard erythromycin neonatal dosage to prevent gonococcal conjunctivitis: 1 cm ribbon applied to the conjunctival sac up to six times daily 

• Standard erythromycin pediatric dosage for infant pneumonia: 50 mg/kg per day taken every six hours for at least three weeks

• Standard erythromycin dosage for community-acquired pneumonia in infants 4 months or older: 40 mg/kg per day taken orally every six hours for 10 days

• Standard erythromycin dosage to prevent rheumatic fever: Same as adult dosage

• Standard erythromycin dosage for pertussis in children 1 month or older: 40–50 mg/kg per day taken every six hours for 14 days

• Maximum erythromycin dosage for pertussis in children 1 month or older: 2 to 4 grams per day

• Standard erythromycin pediatric dosage for diphtheria: 30–50 mg/kg daily divided into two or four doses for 14 days

• Maximum erythromycin pediatric dosage for diphtheria: 2 grams per day

Erythromycin dosage restrictions

The FDA has specified no dosage restrictions or reductions for special populations, including people with renal impairment or hepatic dysfunction. The FDA has warned, however, that erythromycin may cause severe side effects in older adult patients, such as hearing loss or life-threatening heart arrhythmias (pointes de torsades or QT prolongation).

Erythromycin dosage for pets

Veterinarians use erythromycin in dogs and cats to treat bacterial infections. As with humans, they may also use it to promote stomach emptying in animals with gastroparesis. The standard dosages are by weight. Veterinarians will specify that doses be taken every eight or 12 hours. 

How to take erythromycin

Erythromycin tablets or capsules are simple to take. Take each erythromycin dose on an empty stomach, but doses can be taken with a meal if they’re causing stomach upset or abdominal pain. Topical erythromycin is also straightforward to administer. However, erythromycin eye ointment is more challenging to master. It may take a few attempts to get comfortable with its application. 

Here are some general rules to follow:

• Take erythromycin as directed. 

• Take all of the medicine for the entire duration of treatment.

• If a dose is missed, take the missed dose as soon as you remember. If it is almost time for your next dose, wait until then and take a regular dose. Do not take extra medicine to make up for a missed dose.

• Store the medicine in a closed container at room temperature, away from heat, moisture, and direct light. Some brand-name versions of erythromycin are stored in the refrigerator, and some may be kept at room temperature. Storage instructions are written on the package or drug information sheet.

Tablets

• Swallow the coated tablet, delayed-release tablet, or delayed-release capsule whole. Do not crush, break, or chew it.

Oral suspension

• Shake the oral suspension before each use. 

• Measure the liquid medicine with a marked measuring spoon, oral syringe, or medicine cup. Do not use kitchen utensils to measure a dose.

Topical erythromycin

• Use this medicine on the skin only. Never swallow it.

• Wash and dry the affected area before using the medicine.

• When applying topical erythromycin, keep the medicine away from the eyes, nose, or mouth.

• Use the applicator that comes with the medicine if there is one.

• If you use erythromycin pledgets or pads or use your hands, thoroughly wash your hands after applying the medicine.

• Pledgets should be used just once and then thrown away.

Erythromycin eye ointment

• Do not use this medicine if the cap and neck ring are not intact. 

• Wash your hands before applying the medicine.

• Do not touch the tube tip to the eye, eyelid, finger, or any other body part when applying the medicine.

• Tilt your head back.

• Pull down the lower eyelid.

• Squeeze the end of the tube to apply a thin ribbon of ointment on the inside surface of the lower eyelid.

• Close your eyes gently.

Erythromycin dosage FAQs

How long can you take erythromycin?

For most treatments, erythromycin should only be taken for a few days. Prolonged use of erythromycin can result in severe complications like drug-resistant bacterial infections or C. difficile diarrhea and colitis. However, some people may require years or decades of erythromycin treatment. Healthcare professionals will regularly monitor and test for complications or adverse effects.

How do I stop taking erythromycin?

Erythromycin can be stopped at any time without withdrawal effects.

What is the maximum dosage for erythromycin?

The maximum dosage for erythromycin is four grams per day.

What interacts with erythromycin?

Some erythromycin drug interactions are so hazardous that these other drugs are contraindicated. That is, they can’t be taken with erythromycin. These include terfenadine, astemizole, cisapride, pimozide, thioridazine, colchicine, and ergotamine, and dihydroergotamine. In most cases, erythromycin is an inhibitor of the enzymes that break down these drugs in the body. As a result, their levels in the blood can get so high that they hit life-threatening toxicity levels.

Although not contraindicated, erythromycin inhibits the breakdown of several other drugs, including statins such as lovastatin, simvastatin, and atorvastatin. This increases the concentrations of these drugs in the body and the risk of severe adverse effects such as muscle damage.

Erythromycin also inhibits the breakdown of heart rhythm drugs like quinidine or disopyramide, raising the risk of arrhythmias like tachycardia or QT interval prolongation.

It also increases the concentrations and toxicity of drugs like calcium channel blockers (verapamil, amlodipine, diltiazem), benzodiazepines (midazolam and triazolam), digoxin, warfarin (an anticoagulant), bromocriptine (for Type 2 diabetes), carbamazepine, phenytoin (both anticonvulsants), sildenafil (for erectile dysfunction), theophylline, and aminophylline (both for asthma or COPD).

Is it safe to take erythromycin during pregnancy?

Erythromycin is commonly used during pregnancy. There is no definitive evidence that it causes birth defects or affects pregnancy, labor, or delivery. On the other hand, erythromycin is used cautiously in women who are breastfeeding because the drug is present in human breast milk.

Sources

• Erythromycin drug summary, Prescriber’s Digital Reference

• Erythromycin ointment prescribing information, NIH National Library of Medicine

• Erythromycin solution prescribing information, NIH National Library of Medicine

• Erythromycin tablet delayed release prescribing information, NIH National Library of Medicine

• Erythromycin tablet prescribing information, NIH National Library of Medicine