Erythromycin (Oral)


Erythromycin is a versatile antibiotic which combats skin infections, chlamydia infections, pelvic inflammatory disease, syphilis and respiratory tract infections. It can also be useful to prevent group B streptococcal infection in new-born babies when taken by pregnant women. It is available in capsule and tablet form, and can also be administered intravenously and topically. As a topical ointment, it is often administered to babies to prevent eye infections.

Erythromycin functions by inhibiting the growth of bacteria, particularly at higher concentrations, although the precise mechanism of action is not completely understood. It is known that Erythromycin binds to the bacterial rRNA complex at the 50s subunit, inhibiting protein synthesis and structural and/or functional processes which are criticial for the bacteria to survive and reproduce. It also interferes with aminoacyl translocation, and this prevents the transfer of tRNA bound at the A site which is headed for the P site of the rRNA complex. Without this translocation, site A remains occupied, inhibiting the production of useful proteins.

This medication was first isolated from the saccharopolyspora erythraea bacteria in 1952. It is currently listed by the World Health Organization as an essential medicine, on account of its high efficacy, variety of uses and low wholesale price. It is particularly useful for treating bacterial infection in patients who are hypersensitive or allergic to penicillin.

Patients should be aware that taking antibiotics like Erythromycin when they are not needed (such as during bouts of cold, flu or other viral infections) can increase the risk of contracting an infection which is resistant to antibiotic treatment.

Type Of Medicine

  • Antibiotic

Conditions Treated

Side Effects

Along with its desired effects, Erythromycin can also cause some unwanted side effects in certain patients. The most commonly reported side effects by those undergoing treatment with Erythromycin topical cream include the following:

  • Chills
  • Coughing
  • Blistering, loosening or peeling of the skin
  • Difficulty swallowing
  • Diarrhea
  • Fast heartbeat
  • Dizziness
  • Welts or hives
  • Muscle or joint pain
  • Swelling or puffiness of the eyelids or lips, face and/or tongue
  • Irritated or red eyes
  • Reddish skin lesions, sometimes with a purple center
  • Sore throat
  • Reddish skin
  • Dry mouth
  • Skin rash
  • Ulcers, sores or white spots on the lips or in the mouth
  • Tightness within the chest/lungs
  • Wheezing
  • Unusual weakness or tiredness

As the patient continues to take Erythromycin as prescribed, most (if not all) of the previously mentioned symptoms should begin to lessen. If side effects get worse or persist for a prolonged period, the patient is advised to consult their doctor as soon as possible. In some instances, a healthcare professional or pharmacist may be able to recommend ways to alleviate side effects which are causing mild discomfort. For example, regular glasses of cold water, chewing sugar-free gum or sucking on ice cubes can help relieve dry mouth. Other side effects may be treatable with complimentary medicines or over the counter remedies.

Other side effects, which are experienced less frequently, albeit often enough to warrant a mention, include the following:

  • Bloating
  • Stomach cramps
  • Abdominal cramps or tenderness
  • Chest discomfort or pain
  • Dark urine
  • Watery diarrhea, which may also contain blood
  • Fever
  • Fainting
  • General weakness and tiredness
  • Decreased frequency of urination
  • Loss of hearing
  • Increased thirst
  • Irregular heartbeat
  • Vomiting and nausea
  • Yellow skin and eyes
  • Weight loss
  • General pain
  • Light-colored stools
  • Slow heart rate

Because Erythromycin can affect co-ordination and concentration, patients are advised to avoid driving or operating heavy machinery until it has been observed that these side effects do not occur at a level where they could cause impairment. This is because patients who experience such side effects could potentially be putting themselves or other road users at risk while undergoing treatment with this medicine.


As with all medicines, it is imperative that Erythromycin is used by the patient only as prescribed by a physician. This means that patients should avoid taking any more of the medication than advised, either in terms of frequency or dose size. In addition to this, the patient should refrain from taking the medication if advised to do so by their healthcare professional, even if they still have a supply of the medicine remaining.

Erythromycin can be used to treat a variety of infections at varying doses dependent on the severity of the condition:

  • For mild to moderate infection with Campylobacter Gastroenteritis, the patient should take 250mg to 500mg every 6 hours.
  • For treatment of mild to moderate Chancroid, the patient should receive 250mg to 500mg of Erythromycin orally, every six hours.
  • For treatment of mild to moderate Lymphogranuloma Venereum, the patient should receive 250mg to 500mg of Erythromycin, orally, every six hours
  • For treatment of mild to moderate Mycoplasma Pneumonia, the patient should receive 250mg to 500mg of Erythromycin, orally, every six hours.
  • For treatment of Nongonococcal Urethritis, the patient should receive 250mg to 500mg, orally, every six hours.
  • For treatment of Otitis Media, the patient should receive 250mg to 500mg, orally, every six hours.
  • For treatment of Pharyngitis, the patient should receive 400mg to 800mg of Erythromycin, orally, every six hours.
  • For the treatment of general Pneumonia, the patient should receive 400mg to 800mg or Erythromycin, orally, every six hours.
  • For mild to moderate skin/soft tissue infections, the patient should receive 250mg to 500mg of Erythromycin, orally, every six hours.
  • For early onset Syphilis, the patient should receive 250mg to 500mg of Erythromycin, orally, every six hours.
  • For mild to moderate Upper Respiratory Tract infection, the patient should receive 250mg to 500mg of Erythromycin, orally, every six hours.
  • For mild to moderate Bronchitis, the patient should receive 250mg to 500mg of Erythromycin, orally, every six hours.
  • For mild to moderate Chlamydia infection, the patient should receive 250mg to 500mg of Erythromycin, orally, every six hours.
  • For Lyme Disease, the patient should receive between 250mg to 800mg of Erythromycin, orally, every six hours.
  • For treatment of Legionnaire's Disease, the patient should receive between 250mg to 800mg orally, every six hours

Erythromycin can also be used as a preventative medicine prior to invasive surgery:

  • For Bacterial Endocarditis Prophylaxis, the patient should receive 1g of Erythromycin orally, two hours prior to the procedure, followed by 500mg six hours after the initial dose.
  • For bowel preparation, the patient should receive 1g of Erythromycin, orally, at 1, 2 and 11PM the evening before surgery, on the assumption that surgery is taking place at 8AM (doctors may adjust times and dose schedules accordingly).
  • For Rhuematic Fever Prophylaxis, 250mg of Erythromycin should be taken orally twice a day.

While the manufacturer of Erythromycin provides general dosage instructions in the literature contained within the packaging, it should be reiterated that these are merely guidelines which can be altered at the discretion of the patient's doctor. A doctor will take a number of criteria into consideration when deciding upon the most suitable dose, including the height, weight, age and condition of the patient, along with any allergies or co-existing conditions.

Erythromycin should be taken for the full duration of the prescription, unless a doctor advises otherwise. Some patients are tempted to discontinue treatment as symptoms of infection often improve long before the infection has properly cleared, but this increases the risk of the infection returning, and in some instances, this can render infections resistant to Erythromycin and other antibiotics.

Patients are advised to take Erythromycin capsules or tablets whole. They should not be crushed, broken or diluted in liquid.

There is no recommended Erythromycin dose size for children under the age of 12. Instead, the manufacturer leaves the dose size and frequency at the discretion of the doctor who is overseeing the treatment.

Patients are advised against using too much of this medication. If a patient misses a dose, they should simply apply the dose as soon as they realize. If it is closer to the time when the patient would normally apply Erythromycin cream, they should omit the missed dose and simply take the next planned dose, continuing the treatment schedule as normal from thereon in.

Although the potential for overdose with Erythromycin is unlikely, patients who experience signs of overdose (slow or fast heartbeat, difficulty breathing, loss of consciousness, loss of co-ordination, seizures and/or flushed skin) are advised to contact their local poison control center on 1800-222-1222 or emergency services on 911 immediately. Alternatively, a patient may elect to visit their local ER if it is in close enough proximity.


All drugs have the potential to interact with other medicines within the human body, and these interactions can potentially change the effects of one or more medicines within the body, rendering them ineffective at treating the condition they were prescribed for. In other instances, interactions can cause potentially serious or even fatal side effects. Because of these risks, it is vital for patients to keep a full, detailed list of all medicines they are currently undergoing treatment with. This extends to over the counter remedies, complimentary medicines, vitamins and herbal supplements along with prescribed drugs.

Below is a list of medicines which are known to interact negatively with Erythromycin. Patients who are already taking one or more of these medicines are advised to inform their healthcare provider prior to undergoing treatment with topical Erythromycin:

  • Ziprasidone
  • Warfarin
  • Voriconazole
  • Vinorelbine
  • Vincristine Liposome
  • Vincristine
  • Vinblastine
  • Verapamil
  • Venetoclax
  • Vemurafenib
  • Vardenafil
  • Vandetanib
  • Troleandomycin
  • Trandolaprilverapamil
  • Toremifene
  • Thioridazine
  • Teriflunomide
  • Terfenadine
  • Telithromycin
  • Telaprevir
  • Tacrolimus
  • Suvorexant
  • Sparfloxacin
  • Sotalol
  • Sonidegib
  • Solifenacin
  • Sirolimus
  • Simvastatinsitagliptin
  • Simvastatin
  • Simeprevir
  • Sildenafil
  • Saquinavir
  • Ritonavir
  • Ribociclib
  • Red Yeast Rice
  • Ranolazine
  • Quinine
  • Quinidine
  • Quetiapine
  • Pseudoephedrineterfenadine
  • Procainamide
  • Posaconazole
  • Pitavastatin
  • Pimozide
  • Pazopanib
  • Pasireotide
  • Papaverine
  • Panobinostat
  • Oxycodone
  • Osimertinib
  • Ombitasvirparitaprevirritonavir
  • Olaparib
  • Nilotinib
  • Niacinsimvastatin
  • Neratinib
  • Nelfinavir
  • Nefazodone
  • Naltrexoneoxycodone
  • Naloxoneoxycodone
  • Naloxegol
  • Moxifloxacin
  • Mipomersen
  • Mifepristone
  • Mibefradil
  • Methysergide Maleate
  • Methylergonovine
  • Methadone
  • Mesoridazine
  • Macitentan
  • Lurasidone
  • Lovastatinniacin
  • Lovastatin
  • Lopinavirritonavir
  • Loperamidesimethicone
  • Loperamide
  • Lomitapide
  • Levomethadyl Acetate
  • Letrozoleribociclib
  • Leflunomide
  • Ketoconazole
  • Ivacaftorlumacaftor
  • Ivacaftor
  • Ivabradine
  • Itraconazole
  • Indinavir
  • Iloperidone
  • Idelalisib
  • Ibutilide
  • Ibuprofenoxycodone
  • Ibrutinib
  • Hydrocodonepseudoephedrinetriprolidine
  • Hydrocodonepseudoephedrine
  • Hydrocodonepotassium Guaiacolsulfonatepseudoephedrine
  • Hydrocodonepotassium Guaiacolsulfonate
  • Hydrocodonephenylpropanolamine
  • Hydrocodonephenylephrinepyrilamine
  • Hydrocodonephenylephrine
  • Hydrocodonepheniraminephenylephrinephenylpropanolaminepyrilamine
  • Hydrocodoneibuprofen
  • Hydrocodone
  • Homatropinehydrocodone
  • Haloperidol
  • Halofantrine
  • Guanfacine
  • Guaifenesinhydrocodonepseudoephedrine
  • Guaifenesinhydrocodonephenylephrine
  • Guaifenesinhydrocodonepheniraminephenylpropanolaminepyrilamine
  • Guaifenesinhydrocodonepheniraminephenylephrinephenylpropanolamine
  • Guaifenesinhydrocodone
  • Grepafloxacin
  • Gatifloxacin
  • Fosamprenavir
  • Fluvastatin
  • Fluconazole
  • Flibanserin
  • Fingolimod
  • Fentanylropivacaine
  • Fentanyl
  • Ezetimibesimvastatin
  • Everolimus
  • Escitalopram
  • Ergotamine
  • Ergonovine
  • Emtricitabinenelfinavirtenofovir
  • Emtricitabinelopinavirritonavirtenofovir
  • Eliglustat
  • Eletriptan
  • Efavirenzemtricitabinetenofovir
  • Efavirenz
  • Edoxaban
  • Droperidolfentanyl
  • Droperidol
  • Dronedarone
  • Dolasetron
  • Dofetilide
  • Docetaxel
  • Disopyramide
  • Diphenhydraminehydrocodonephenylephrine
  • Diltiazemenalapril
  • Diltiazem
  • Dihydroergotamine
  • Dicumarol
  • Dextromethorphanquinidine
  • Dexchlorpheniraminehydrocodonephenylephrine
  • Dexbrompheniraminehydrocodonephenylephrine
  • Delavirdine
  • Deflazacort
  • Dasatinib
  • Dasabuvirombitasvirparitaprevirritonavir
  • Dalfopristinquinupristin
  • Cyclosporine
  • Crizotinib
  • Conivaptan
  • Colchicineprobenecid
  • Colchicine
  • Cobimetinib
  • Cobicistatdarunavir
  • Cobicistat
  • Clarithromycin
  • Citalopram
  • Cisapride
  • Cilostazol
  • Cholera Vaccine, Live
  • Chlorpheniraminehydrocodonepseudoephedrine
  • Chlorpheniraminehydrocodonephenylephrine
  • Chlorpheniraminehydrocodone
  • Chlorpheniramineguaifenesinhydrocodonepseudoephedrine
  • Cerivastatin
  • Ceritinib
  • Carbinoxaminehydrocodonepseudoephedrine
  • Carbinoxaminehydrocodonephenylephrine
  • Carbamazepine
  • Caffeineergotamine
  • Cabergoline
  • Butorphanol
  • Bupivacainefentanyl
  • Brompheniraminehydrocodonepseudoephedrine
  • Brompheniraminehydrocodonephenylephrine
  • Brexpiprazole
  • Bosutinib
  • Boceprevir
  • Betrixaban
  • Bepridil
  • Belladonnaergotaminephenobarbital
  • Belladonnacaffeineergotaminepentobarbital
  • Bedaquiline
  • Axitinib
  • Avanafil
  • Atorvastatinezetimibe
  • Atorvastatin
  • Atazanavircobicistat
  • Astemizole
  • Aspirinoxycodone
  • Aspirinhydrocodone
  • Artemetherlumefantrine
  • Arsenic Trioxide
  • Anisindione
  • Anagrelide
  • Amprenavir
  • Amoxicillinclarithromycinomeprazole
  • Amoxicillinclarithromycinlansoprazole
  • Amlodipineatorvastatin
  • Amiodarone
  • Alfuzosin
  • Alfentanil
  • Acetaminophenoxycodone
  • Acetaminophenhydrocodone
  • Acetaminophencaffeinechlorpheniraminehydrocodonephenylephrine
  • Acalabrutinib

Along with medicines, certain foods can also interact with Erythromycin. Grapefruit and grapefruit juice should be avoided when undergoing treatment with this medicine, as it can increase the level of Erythromycin within the blood. However, how this could affect the patient is not currently known.


Before undergoing treatment with Erythromycin, patients are advised to inform their doctor if they have ever suffered from any of the following conditions:

Erythromycin is classed as a Pregnancy Category B medication by the FDA. While this medicine can cross the placenta in small amounts, in many cases Erythromycin levels are undetectable in umbilical cord serum. When present during studies, the concentrations ranged from 1% to 6%, meaning that this medicine has a low risk of directly affecting an unborn fetus. However, pregnant women who undergo treatment with Erythromycin may be more prone to hepatoxicity. Pregnant women with pre-existing liver conditions should therefore take Erythromycin with caution, and consult their doctor prior to treatment.

There is no evidence to suggest that Erythromycin is excreted into breast milk. However, patients who are currently breastfeeding are advised to only use Erythromycin if the benefits of doing so outweigh any other potential risks. Just because no evidence exists to suggest this medicine may cause issues, the potential still exists. Patients should always consult with their doctor or healthcare provider prior to taking any medication while breastfeeding.


Erythromycin tablets should be stored at room temperature, away from excess heat, light or moisture. This medication is therefore not suitable for storage in a bathroom, and should instead be kept in a dedicated medicine cabinet where possible, or in a cupboard out of sight and reach of children or animals.

If a doctor determines that treatment with Erythromycin is no longer necessary, the patient should undertake the necessary steps to safely and hygenically dispose of the unwanted medicine in accordance with state law. Many pharmacies offer 'œtake back' schemes where expired, unwanted or unused medicines can be disposed of or recycled, usually at no cost to the patient. For further information on how to dispose of medicines, patients are advised to contact their pharmacist or local waste disposal center.


While Erythromycin is incredibly beneficial to patients suffering from bacterial infection, it can also pose a risk to those who do not communicate effectively with their physicians. As a treatment which alleviates the symptoms of various infections, Erythromycin reduces pain, swelling and other symptoms, but it can also rid the body of 'œgood' bacteria or flora within the gut, leading to diarrhea and other gastrointestinal issues. Because of these risks, it is important for the patient to inform his or her doctor about their medical history including any hereditary illnesses within the family. There are a reasonable number of conditions which can be exacerbated by use of Erythromycin, which makes it necessary for the patient to be honest and up-front with their healthcare provider.

When taken as prescribed, Erythromycin fights infections which can be incredibly serious or even fatal, allowing the patient to make a full recovery and enjoy a better quality of life. To achieve these results, patient and doctor are advised to work together in order to develop the best possible course of treatment, encapsulating dosage and frequency of use.