Skip to Content

Ketek Pak Side Effects

Generic Name: telithromycin

Note: This page contains information about the side effects of telithromycin. Some of the dosage forms included on this document may not apply to the brand name Ketek Pak.

For the Consumer

Applies to telithromycin: oral tablet

In addition to its needed effects, some unwanted effects may be caused by telithromycin (the active ingredient contained in Ketek Pak). In the event that any of these side effects do occur, they may require medical attention.

Severity: Major

You should check with your doctor immediately if any of these side effects occur when taking telithromycin:

  • Abdominal or stomach pain
  • blistering, peeling, or loosening of the skin
  • blurred vision
  • chest pain or discomfort
  • chills
  • confusion
  • convulsions
  • cough
  • dark urine
  • decreased urine
  • difficulty with breathing, chewing, swallowing, or talking
  • dizziness
  • double vision
  • drooping eyelids
  • dry mouth
  • fainting
  • faintness or lightheadedness when getting up suddenly from a lying or sitting position
  • fast, slow, or irregular heartbeat
  • fever with or without chills
  • increased thirst
  • itching
  • joint pain
  • large, hive-like swelling on the face, eyelids, lips, tongue, throat, hands, legs, feet, or sex organs
  • light-colored stools
  • loss of appetite
  • mood changes
  • muscle pain or cramps
  • muscle weakness
  • nausea
  • nervousness
  • numbness or tingling in the hands, feet, or lips
  • red, irritated eyes
  • shortness of breath
  • skin rash
  • sores, ulcers, or white spots in the mouth or on the lips or tongue
  • stomach cramps, tenderness, or pain
  • sweating
  • tightness in the chest
  • unusual tiredness or weakness
  • upper right abdominal or stomach pain
  • vomiting
  • watery or bloody diarrhea
  • weakness or heaviness of the legs
  • wheezing
  • yellow eyes and skin
Incidence not known:
  • Black, tarry stools
  • clay-colored stools
  • continuous vomiting
  • dark-colored urine
  • decreased appetite
  • general feeling of tiredness or weakness
  • swelling of the feet or lower legs
  • unpleasant breath odor
  • vomiting of blood

Severity: Minor

Some of the side effects that can occur with telithromycin may not need medical attention. As your body adjusts to the medicine during treatment these side effects may go away. Your health care professional may also be able to tell you about ways to reduce or prevent some of these side effects. If any of the following side effects continue, are bothersome or if you have any questions about them, check with your health care professional:

More common:
  • Diarrhea
Less common:
  • Abnormal dreams
  • acid or sour stomach
  • belching
  • bloated, full feeling, or pressure in the stomach
  • burning, crawling, itching, numbness, prickling, "pins and needles", or tingling feelings
  • burning feeling in the chest or stomach
  • change in color, amount, or odor of vaginal discharge
  • change in sense of smell
  • change in taste
  • difficulty focusing the eyes
  • difficulty having a bowel movement (stool)
  • disturbed attention span
  • dry lips
  • dry skin
  • excess air or gas in the stomach or intestines
  • feeling of constant movement of self or surroundings
  • feeling of warmth, redness of the face, neck, arms, and occasionally, upper chest
  • frequent urination
  • headache
  • heartburn
  • increased amount of pale, dilute urine
  • indigestion
  • itching of the vagina or outside genitals
  • lack or loss of strength
  • lightheadedness
  • loose stools
  • loss of appetite
  • loss of sense of taste
  • pain during sexual intercourse
  • pain or tenderness around the eyes and cheekbones
  • passing gas more often than usual
  • redness of the skin
  • redness, swelling, or soreness of the tongue
  • sensation of spinning
  • shakiness in the legs, arms, hands, or feet
  • skin rash, encrusted, scaly, and oozing
  • sleeplessness
  • sore mouth or tongue
  • sore throat
  • stomach upset or pain
  • stuffy or runny nose
  • swelling or puffiness of the face
  • tenderness in the stomach area
  • thick, white curd-like vaginal discharge, without odor or with mild odor
  • tooth discoloration
  • trouble sleeping
  • weight loss
  • white patches in the mouth and on the tongue

For Healthcare Professionals

Applies to telithromycin: oral tablet


Hepatic side effects have included severe liver toxicity, abnormal liver function tests such as increased transaminases and increased liver enzymes alanine transaminase (ALT) and aspartate transaminase (AST), increased ALT greater than or equal to 3 times the upper limit of normal or ULN (1.6%), reversible hepatitis with or without jaundice (0.07%), and hepatocellular and/or cholestatic hepatitis with or without jaundice. Hepatic dysfunction and severe (and in some cases fatal) hepatotoxicity, including fulminant hepatitis, hepatic necrosis, and hepatic failure, have been reported during postmarketing experience. Such hepatic reactions were observed during or immediately following therapy, and some cases of liver injury progressed rapidly and occurred after administration of only a few doses of telithromycin (the active ingredient contained in Ketek Pak) Clinical trial and postmarketing reports of hepatic dysfunction were usually mild to moderate.[Ref]

Cases of severe liver toxicity have been reported: Four were fatal and one patient required a liver transplant.

A case report of a 46-year-old man with hepatotoxicity due to telithromycin therapy, for an ear and sinus infection was reported. The patient presented with a 4-day history of malaise, dark urine, jaundice, mild pruritus, and anorexia. The patient denied toxin exposure, intravenous drug abuse, or hepatic injury. ALT was 948 U/L, AST 200 U/L, total bilirubin 65 mmol/L, and alkaline phosphatase 291 U/L. These values warranted withdrawal of telithromycin and within two weeks the ALT decreased to 450 U/L and his jaundice resolved. After eight weeks the patient's liver tests were normalized.[Ref]


Gastrointestinal side effects have included diarrhea (10.8%), nausea (7.9%), vomiting (2.9%), loose stools (2.3%), and dysgeusia (1.6%). Abdominal distension, dyspepsia, gastrointestinal upset, flatulence, constipation, gastroenteritis, gastritis, anorexia, glossitis, oral candidiasis, stomatitis, and watery stools have been reported in less than 2% of patients. Pseudomembranous colitis has also been reported. Pancreatitis has been reported during postmarketing experience.[Ref]


Ocular side effects have included blurred vision, diplopia, or difficulty focusing in less than 2% of patients. Most visual side effects were reported after the first or second dose, lasted for several hours, and recurred with subsequent doses in some patients. Symptoms continued throughout the entire course of therapy in some patients and resolved spontaneously during therapy in others. Females and patients younger than 40 years had a higher rate of these side effects.[Ref]

Nervous system

Nervous system side effects have included headache (5.5%) and dizziness (3.7%). Somnolence, insomnia, dry mouth, vertigo, and increased sweating have been reported in less than 2% of patients. Paresthesia and anxiety have rarely been reported. Loss of consciousness/syncope (in some cases associated with vagal syndrome) and taste/smell perversion and/or loss have been reported during postmarketing experience.[Ref]


Respiratory side effects have included rhinitis (0.05%) and upper respiratory infection (0.05%). Life-threatening acute respiratory failure has been reported in patients with myasthenia gravis.[Ref]


Hematologic side effects have included increased platelet count (less than 2%) and increased eosinophil count (less than 0.2%).[Ref]


Other side effects have included abdominal pain, upper abdominal pain, and fatigue in less than 2% of patients.


Dermatologic side effects have included rash (less than 2%) and eczema, erythema multiforme, pruritus, and urticaria in less than 0.2% of patients.[Ref]


Cardiovascular side effects have rarely included flushing, hypotension, bradycardia, and increased QTc interval. Atrial arrhythmia, palpitations, and torsades de pointes have been reported during postmarketing experience.[Ref]


Genitourinary side effects have included vaginal candidiasis, vaginitis, and fungal vaginosis in less than 2% of patients.[Ref]


Musculoskeletal side effects have included muscle cramps, arthralgia, myalgia, and rare reports of exacerbation of myasthenia gravis during postmarketing experience.[Ref]


Metabolic side effects have included increased blood alkaline phosphatase and elevated blood bilirubin in less than 0.2% of patients.[Ref]


Hypersensitivity side effects have included facial edema and rare reports of severe allergic (hypersensitivity) reactions, including angioedema and anaphylaxis during postmarketing experience.[Ref]


Psychiatric side effects have included confusion and hallucinations (mostly visual) during postmarketing experience.


1. Onur O, Guneysel O, Denizbasi A, Celikel C "Acute hepatitis attack after exposure to telithromycin." Clin Ther 29 (2007): 1725-1729

2. "Product Information. Ketek (telithromycin)." Aventis Pharmaceuticals, Bridgewater, NJ.

3. Clay KD, Hanson JS, Pope SD, Rissmiller RW, Purdum PP 3rd, Banks MD "Brief Communication: Severe hepatotoxicity of telithromycin: three case reports and literature review. Available from: URL:" ([2006 Mar 21]):

4. Clay KD, Hanson JS, Pope SD, Rissmiller RW, Purdum PP 3rd, Banks PM "Brief communication: severe hepatotoxicity of telithromycin: three case reports and literature review." Ann Intern Med 144 (2006): E1-E6

5. Owens RC Jr, Nolin TD "Antimicrobial-Associated QT Interval Prolongation: Pointes of Interest." Clin Infect Dis 43 (2006): 1603-1611

6. Nieman RB, Sharma K, Edelberg H, Caffe SE "Telithromycin and myasthenia gravis." Clin Infect Dis 37 (2003): 1579

Not all side effects for Ketek Pak may be reported. You should always consult a doctor or healthcare professional for medical advice. Side effects can be reported to the FDA here.

Disclaimer: Every effort has been made to ensure that the information provided is accurate, up-to-date and complete, but no guarantee is made to that effect. In addition, the drug information contained herein may be time sensitive and should not be utilized as a reference resource beyond the date hereof. This material does not endorse drugs, diagnose patients, or recommend therapy. This information is a reference resource designed as supplement to, and not a substitute for, the expertise, skill , knowledge, and judgement of healthcare practitioners in patient care. The absence of a warning for a given drug or combination thereof in no way should be construed to indicate safety, effectiveness, or appropriateness for any given patient. does not assume any responsibility for any aspect of healthcare administered with the aid of materials provided. The information contained herein is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. If you have questions about the substances you are taking, check with your doctor, nurse, or pharmacist.