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Generic Name

bethanechol (beth AN ah col)


Trade Name



What is clarithromycin?

This drug is an antibiotic which kills bacteria and clears up infection within the body.


What is it used for?

Clarithromycin is used for many different bacterial infections. When used with other drugs, it can cure the stomach infection called Helicobacter pylori gastritis.


How do I take it?

Follow your physician’s instructions carefully. Clarithromycin may be taken with or without food. As with all antibiotics, it is important to take the full prescribed dose. The tablet may be crushed and sprinkled on soft food. Store tablets in a tightly sealed container away from light at room temperature. Do not refrigerate suspension. Shake well before each use. Keep all medications away from children. Never share your medications with anyone else.


What do I do for a missed dose?

Clarithromycin, like all antibiotics, works best when there is a constant amount of drug in the blood. To keep the blood level constant, it is important not to miss any doses. If you do miss a dose, take it as soon as you remember. If it is almost time for your next dose, take the one you missed and take the next one 5 to 6 hours later and then resume your regular schedule.


Are there interactions with food or beverages?

There are no known interactions with any food or beverages.


Are there interactions with other drugs?

An interaction generally means that one drug may increase or decrease the effect of another drug. Also, the more medications a person takes, the more likely there will be a drug interaction. This drug is metabolized in a certain site in the liver where may other drugs are also broken down. This can result in serious medical problems. See below for certain possible drug-drug interactions.

Interactions with clarithromycin may occur with the following:

  • astemizole (Hismanal)
  • blood thinners (Coumadin)
  • carbamazepine (Tegretol)
  • cisapride (Propulsid)
  • cyclosporine (Sandimmune, Neoral)
  • digoxin (Lanoxin)
  • disopyramide (Norpace)
  • ergotamine (Cafergot)
  • fluconazole (Diflucan)
  • lovastatin (Mevacor)
  • phenytoin (Dilantin)
  • theophylline (Theo-Dur)
  • triazolam (Halcion)
  • valproate (Depakene)
  • zidovudine (Retrovir)


Is there a problem if I have another disorder or disease?

At times, a drug may have a different or enhanced effect when other diseases are present. At other times, the drug may worsen or effect another disease. This drug should not be used with ranitidine-bismuth citrate (Tritec) in patients who have a history of porphyria. Since the drug is excreted by the kidney and liver, patients with severe chronic disease of these organs (kidney patients on dialysis, cirrhosis) should discuss it with the physician.


What about allergies?

People who have known allergies or asthma may be at an increased risk for a reaction from any new medication. The physician should always know a patient’s allergy history. Signs of an allergic reaction are skin rash, hives and itching. Of course, a person should not take clarithromycin if there has been a previous reaction to this or a similar drug such as erythromycin or Zithromax.


What if I’m pregnant, considering pregnancy or breast-feeding?

Most females now know that, if possible, no drug, including alcohol, should be taken during pregnancy or lactation. The potential danger, of course, is an injury to the baby. However, some drugs are much safer than others in this regard. So, the FDA has a grading system for each drug which reflects what is known medically. It ranks drugs from A, where medical studies show no evidence for danger to the fetus or mother, to B, C, D and X, where the medical evidence indicates that the risk to the fetus outweighs any benefit to the mother. Clarithromycin is ranked C. Always consult your physician before taking any drug during or when planning pregnancy.


What are the effects on sexual function?

There are no known effects of acetaminophen on sexual function.


Are there other precautions?

Mild diarrhea is a fairly common side effect of clarithromycin. It may stop after your body gets used to the drug. However, if clarithromycin gives you prolonged or severe diarrhea lasting over 24 hours, stop taking the drug and contact your physician. Prolonged or repeated use of antibiotics may result in bacterial or fungal overgrowth and superinfection. These are usually due to yeast organisms and occur in the mouth, intestinal tract or vagina.


How long is it safe to take clarithromycin?

At times, physicians will want to use an antibiotic long-term to control chronic infection as in Crohn’s disease or a Crohn’s fistula. The drug can generally be used this way although it will often reduce or change the normal bacteria in the colon. Clarithromycin is now used in combination with certain other drugs for a 14 day period to cure the stomach bacteria infection called Helicobacter pylori.


How about side effects?

Adverse reactions can occur with any drug, even over-the-counter medications. Some of these are mild such as a stomach upset, which may be avoided by taking the medication with food. Minor reactions may go away on their own but if they persist, contact the physician. For major reactions, the patient should contact the physician immediately.

For clarithromycin, the following are the observed side effects:


  • diarrhea
  • nausea
  • abnormal taste
  • abdominal discomfort
  • indigestion
  • headache


  • severe diarrhea or abdominal cramps
  • rapid heart rate


A physician’s comment…

Most antibiotics taken by mouth are fairly safe. However, resistance to these drugs does occur when they are used too often. Therefore, they should only be used for specific purposes and for the length of time decided by the physician.