Many medications can cause side effects. A side effect is an unwanted response to a medication when it is taken in normal doses. Side effects can be mild or severe, temporary or permanent. The side effects listed below are not experienced by everyone who takes Erythro S. If you are concerned about side effects, discuss the risks and benefits of Erythro S with your doctor.

The following side effects have been reported by at least 1% of people taking Erythro S. Many of these side effects can be managed, and some may go away on their own over time.

Contact your doctor if you experience these side effects and they are severe or bothersome. Your pharmacist may be able to advise you on managing side effects.

• abdominal or stomach cramping and discomfort
• Diarrhea
• nausea or vomiting

Although most of these side effects listed below don't happen very often, they could lead to serious problems if you do not check with your doctor or seek medical attention.

Check with your doctor as soon as possible if any of the following side effects occur:

• confusion
• continued diarrhea even after you have finished taking Erythro S
• hallucinations
• irregular or fast heartbeat
• loss of hearing (temporary)
• nausea or vomiting (severe)
• ringing in the ear
• seizures
• skin rash, redness, or itching
• stomach pain (severe)
• symptoms of liver damage (e.g., yellow skin or eyes, abdominal pain, dark urine, clay-coloured stools, loss of appetite, nausea and vomiting, or itching)
• unusual tiredness or weakness
• Vertigo

Stop taking the medication and seek immediate medical attention if any of the following occur:

• symptoms of a serious allergic reaction (e.g., swelling of the face or throat, Hives, or difficulty breathing)

Some people may experience side effects other than those listed. Check with your doctor if you notice any symptom that worries you while you are taking Erythro S.

Erythro S is available as 250 mg and 500 mg tablets.

Erythromycin stearate should not be taken by anyone who:

• is allergic to erythromycin or to any of the ingredients of the medication
• is allergic to clarithromycin or other macrolide antibiotics
• is taking astemizole*, terfenadine, cisapride, Pimozide, ergotamine, or dihydroergotaime

*Astemizole, terfenadine, and cisapride are no longer marketed in Canada.

There may be an interaction between erythromycin stearate and any of the following:

If you are using any of these medications, speak with your doctor or pharmacist. Depending on your specific circumstances, your doctor may want you to:

• stop taking one of the medications,
• change one of the medications to another,
• change how you are taking one or both of the medications, or
• leave everything as is.

An interaction between two medications does not always mean that you must stop taking one of them. Speak to your doctor about how any drug interactions are being managed or should be managed.

Medications other than those listed above may interact with Erythro S. Tell your doctor or prescriber about all prescription, over-the-counter (non-prescription), and herbal medications that you are taking. Also tell them about any supplements you take. Since caffeine, decongestants, alcohol, the Nicotine from cigarettes, or street drugs can affect the action of many medications, you should let your prescriber know if you use them.

Before you begin using a medication, be sure to inform your doctor of any medical conditions or Allergies you may have, any medications you are taking, whether you are pregnant or breast-feeding, and any other significant facts about your health. These factors may affect how you should use Erythro S.

Allergic reactions: Hives and mild rashes as well as infrequent serious allergic reactions have been reported by people taking Erythro S. Erythromycin should be taken with caution by anyone who has had any form of allergy to medications. If you experience an allergic reaction to erythromycin, stop taking the medication and contact your doctor.

Diarrhea: Erythro S is associated a serious infection called Clostridium difficile associated diarrhea, caused by the bacteria C. difficile. This can occur as late as 2 months after your last dose of Erythro S. If you have loose, watery bowel movements that are green, foul-smelling, or bloody that may be accompanied by Fever after taking erythromycin, get medical attention as soon as possible.

Liver problems: People with reduced liver function should discuss with their doctor how Erythro S may affect their medical condition, how their medical condition may affect the dosing and effectiveness of Erythro S, and whether any special monitoring is needed.

There have been reports of liver problems occurring in a small percentage of people taking erythromycin products, particularly erythromycin estolate. Anyone experiencing yellowing of the pigments of their eyes or skin (suggestive of jaundice) should see their doctor.

Myasthenia Gravis: Use of Erythro S may aggravate this condition.

Overgrowth of organisms: Prolonged or repeated use of erythromycin may result in an overgrowth of bacteria or fungi and organisms that are not killed by the medication. This can cause problems such as yeast infections.

Pregnancy: Erythro S should not be used during pregnancy unless the benefits outweigh the risks. If you become pregnant while taking Erythro S, contact your doctor immediately.

Breast-feeding: Erythro S passes into breast milk. If you are a breast-feeding mother and are taking erythromycin, it may affect your baby. Talk to your doctor about whether you should continue breast-feeding.

Children: The safety of erythromycin for use by newborns has not been established.