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Helidac Side Effects

Generic name: bismuth subsalicylate / metronidazole / tetracycline

Medically reviewed by Last updated on Oct 2, 2022.

Note: This document contains side effect information about bismuth subsalicylate / metronidazole / tetracycline. Some dosage forms listed on this page may not apply to the brand name Helidac.

Applies to bismuth subsalicylate / metronidazole / tetracycline: oral capsule, oral tablet, oral tablet chewable.


Oral route (Kit)

Metronidazole has been shown to be carcinogenic in mice and rats. It is unknown whether metronidazole is associated with carcinogenicity in humans.

Serious side effects of Helidac

Along with its needed effects, bismuth subsalicylate/metronidazole/tetracycline may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

Check with your doctor immediately if any of the following side effects occur while taking bismuth subsalicylate / metronidazole / tetracycline:

Less common

  • Black, tarry stools
  • body aches or pain
  • burning, itching, numbness, prickling, "pins and needles", or tingling feelings
  • burning upper stomach pain
  • chills
  • cough
  • difficulty in breathing
  • ear congestion
  • fever
  • headache
  • loss of appetite
  • loss of voice
  • nausea
  • pain or tenderness around the eyes and cheekbones
  • runny or stuffy nose
  • sneezing
  • sore throat
  • tightness in the chest
  • unusual tiredness or weakness
  • vomiting
  • vomiting of blood or material that looks like coffee grounds
  • weight loss


  • Bladder pain
  • bleeding from the rectum
  • bloody or cloudy urine
  • blurred vision
  • bruising
  • burning, dry, or itching eyes
  • chest pain or discomfort
  • confusion
  • diarrhea
  • difficult, burning, or painful urination
  • discharge, excessive tearing
  • dizziness
  • fainting
  • frequent urge to urinate
  • general feeling of discomfort or illness
  • increased sensitivity of the skin to sunlight
  • itching, skin rash
  • joint pain
  • large, flat, blue or purplish patches in the skin
  • lower back or side pain
  • muscle aches and pains
  • nervousness
  • pain or discomfort in the arms, jaw, back, or neck
  • pounding in the ears
  • redness or other discoloration of the skin
  • redness, pain, swelling of the eye, eyelid, or inner lining of the eyelid
  • redness, swelling, or soreness of the tongue
  • severe constipation
  • severe numbness, especially on one side of the face or body
  • severe sunburn
  • shivering
  • slow or fast heartbeat
  • sore throat
  • stomach pain
  • sweating
  • tooth disorder
  • trouble sleeping
  • trouble swallowing
  • tumor
  • white patches in the mouth or on the tongue

Incidence not known

  • Blistering, peeling, loosening of the skin
  • chest pain
  • clumsiness
  • decreased vision
  • joint or muscle pain
  • red irritated eyes
  • red skin lesions, often with a purple center
  • redness or soreness around fingernails or loosening of the fingernails
  • sores, ulcers, or white spots in the mouth or on the lips
  • swollen glands
  • unusual bleeding or bruising

Get emergency help immediately if any of the following symptoms of overdose occur while taking bismuth subsalicylate / metronidazole / tetracycline:

Symptoms of overdose

  • Blue lips, fingernails, or skin
  • burning, numbness, tingling, or painful sensations
  • continuing ringing or buzzing or other unexplained noise in the ears
  • coughing that sometimes produces a pink frothy sputum
  • difficult, noisy, fast, or deep breathing
  • hearing loss
  • increased sweating
  • irregular, fast or slow, or shallow breathing
  • loss of consciousness
  • pale skin
  • seizures
  • shakiness and unsteady walk
  • slow heartbeat
  • swelling in the legs and ankles
  • unsteadiness, trembling, or other problems with muscle control or coordination
  • weakness in the arms, hands, legs, or feet

Other side effects of Helidac

Some side effects of bismuth subsalicylate / metronidazole / tetracycline may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects.

Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:

Less common

  • Belching
  • bloating
  • burning or itching around the anus
  • change in or loss of taste
  • darkening of the tongue
  • excess air or gas in the stomach or bowels
  • feeling of fullness
  • heartburn
  • indigestion
  • lack or loss of strength
  • passing gas
  • stomach discomfort or upset


  • Blemishes on the skin
  • difficulty in moving
  • drowsiness
  • dry mouth
  • joint swelling or stiffness
  • pimples

For Healthcare Professionals

Applies to bismuth subsalicylate / metronidazole / tetracycline: oral kit.


The most commonly reported side effects included nausea, abdominal pain, and diarrhea.[Ref]


Very common (10% or more): Nausea (up to 12%)

Common (1% to 10%): Abdominal pain, anal discomfort, constipation, diarrhea, duodenal ulcer, dyspepsia, flatulence, gastrointestinal hemorrhage, melena, stool abnormality/darkening/black stools, tongue discoloration/darkening, vomiting

Frequency not reported: Dry mouth, dysphagia, eructation, gastrointestinal monilia, glossitis, intestinal obstruction, rectal hemorrhage, stomatitis, tooth disorder


Frequency not reported: Abdominal pain, constipation, candida overgrowth, diarrhea, dry mouth, furry tongue, glossitis, nausea, pancreatitis, stomatitis, vomiting


Frequency not reported: Anogenital region inflammatory lesions/inflammatory lesions with Candida overgrowth, black hairy tongue, diarrhea, dysphagia, enterocolitis, esophagitis, esophageal ulceration, glossitis, nausea, vomiting[Ref]

Nervous system

Common (1% to 10%): Dizziness, dysgeusia/taste perversion/metallic taste, headache, paresthesia

Frequency not reported: Cerebral ischemia, somnolence, syncope


Frequency not reported: Aseptic meningitis, ataxia, convulsive seizures, dizziness, dysarthria, encephalopathy, headache, incoordination, metallic taste, peripheral neuropathy, syncope, vertigo


Frequency not reported: Intracranial hypertension, pseudotumor cerebri[Ref]


Common (1% to 10%): Asthenia, pain

Frequency not reported: Infection, malaise


Frequency not reported: Fever, weakness


Frequency not reported: Tinnitus[Ref]


Common (1% to 10%): Sinusitis, upper respiratory infection

Frequency not reported: Rhinitis


Frequency not reported: Nasal congestion[Ref]


Common (1% to 10%): Insomnia

Frequency not reported: Nervousness


Frequency not reported: Confusion, decreased libido, depression, insomnia, irritability[Ref]


Common (1% to 10%): Anorexia


Frequency not reported: Anorexia


Frequency not reported: Anorexia[Ref]


Frequency not reported: Acne, ecchymosis, photosensitivity reaction, pruritus, rash


Frequency not reported: Erythematous rash, pruritus, Stevens-Johnson syndrome, toxic epidermal necrolysis, urticaria


Frequency not reported: Drug rash with eosinophilia and systemic symptoms (DRESS) syndrome, erythema multiforme, exfoliative dermatitis, Henoch-Schonlein purpura, maculopapular/erythematous rash, nail discoloration, onycholysis, photosensitivity, Stevens-Johnson syndrome, systemic lupus erythematosus exacerbation, toxic epidermal necrolysis, urticaria[Ref]


Frequency not reported: Chest pain, hypertension, myocardial infarction


Frequency not reported: T-wave flattening, flushing


Frequency not reported: Pericarditis[Ref]


Frequency not reported: Arthritis, rheumatoid arthritis, tendonitis


Frequency not reported: Joint pain


Frequency not reported: Myasthenic syndrome[Ref]


Frequency not reported: Urinary tract infection


Frequency not reported: Darkened urine, dyspareunia, dysuria, incontinence, proctitis, sense of pelvic pressure, vaginal/vulvar dryness[Ref]


Frequency not reported: ALT increase, AST increase


Frequency not reported: Hepatotoxicity, liver failure[Ref]


Frequency not reported: Flu syndrome


Frequency not reported: Serum sickness-like reaction[Ref]


Frequency not reported: Conjunctivitis


Frequency not reported: Optic neuropathy[Ref]


Frequency not reported: Neoplasm[Ref]



Frequency not reported: Reversible neutropenia/leukopenia, reversible thrombocytopenia


Frequency not reported: Eosinophilia, hemolytic anemia, neutropenia, thrombocytopenia, thrombocytopenic purpura



Frequency not reported: Cystitis


Frequency not reported: Increased blood urea nitrogen



Frequency not reported: Anaphylaxis, angioedema[Ref]

More about Helidac (bismuth subsalicylate / metronidazole / tetracycline)

Patient resources

Professional resources

Related treatment guides


1. "Product Information. Helidac (bismuth subsalicylate/metronidazole/TCN)." Prometheus Inc (2022):

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

Some side effects may not be reported. You may report them to the FDA.