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Helidac Side Effects

Generic Name: bismuth subsalicylate / metronidazole / tetracycline

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

For the Consumer

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

In addition to its needed effects, some unwanted effects may be caused by bismuth subsalicylate / metronidazole / tetracycline. In the event that any of these side effects do occur, they may require medical attention.

Major Side Effects

You should check with your doctor immediately if any of these side effects occur when taking bismuth subsalicylate / metronidazole / tetracycline:

More common:
  • Abdominal or stomach pain
  • bloody or black, tarry stools
  • diarrhea
  • nausea
Less common:
  • Burning, prickling, or tingling sensations
  • dizziness
  • vomiting
  • Bloody vomit
  • convulsions (seizures)
  • fainting
  • heart attack
  • irritation of the mouth or tongue
  • joint pain and swelling
  • sensitivity of the skin to sunlight
  • skin rash
  • trouble with swallowing

If any of the following symptoms of overdose occur while taking bismuth subsalicylate / metronidazole / tetracycline, get emergency help immediately:

Symptoms of overdose:
  • Clumsiness or unsteadiness
  • confusion
  • continuing ringing or buzzing in ears
  • fast heartbeat
  • fast or deep breathing
  • fever
  • pain, numbness, or tingling in the arms, legs, hands, or feet
  • unusual tiredness
  • vomiting

Minor Side Effects

Some of the side effects that can occur with bismuth subsalicylate / metronidazole / tetracycline 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:

Less common or rare:
  • Burning or itching around the anus
  • constipation
  • general feeling of discomfort or illness
  • loss of appetite
  • nervousness
  • trouble sleeping

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: ALT increase, AST increase

Frequency not reported: Hepatotoxicity, liver failure[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: 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]


1. "Product Information. Helidac (bismuth subsalicylate/metronidazole/TCN)." Prometheus Inc, San Diego, CA.

Not all side effects for Helidac 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.