Bismuth Subcitrate Potassium / Metronidazole / Tetracycline Side Effects

Medically reviewed by Drugs.com. Last updated on Feb 2, 2025.

Applies to bismuth subcitrate potassium / metronidazole / tetracycline: oral capsule.

Precautions

It is very important that your doctor check your progress at regular visits for any problems or unwanted effects that may be caused by this medicine.

Do not use this medicine if you are also using methoxyflurane or have used disulfiram in the last 2 weeks. Do not drink alcohol while you are using this medicine and for at least 3 days after your last dose.

Using this medicine while you are pregnant can harm your unborn baby. Use an effective form of birth control to keep from getting pregnant. If you think you have become pregnant while using this medicine, tell your doctor right away.

Birth control pills may not work properly if you take them while you are using this medicine. You should use a different or additional means of birth control (eg, condoms, diaphragm, or a contraceptive foam or jelly) while you are using this medicine. If you have any questions about this, check with your doctor.

Bismuth subcitrate may cause your tongue to become a darker color or even black. It may also make your stools (bowel movements) black. This is only temporary and will not hurt you. Your tongue and stools will go back to normal when you stop using this medicine. Ask your doctor about this if you have any concerns.

Do not drink milk or eat dairy products with this medicine.

Check with your doctor right away if you start to have a stiff neck, drowsiness, fever, severe headache, nausea, vomiting, painful eye movements, or eye sensitivity to light. These could be symptoms of a serious condition called aseptic meningitis syndrome (AMS).

Check with your doctor right away if you are having burning, numbness, tingling, or painful sensations in the arms, hands, legs, or feet. These could be symptoms of a condition called peripheral neuropathy.

Tetracycline may make your skin more sensitive to sunlight. Exposure to sunlight, even for brief periods of time, may cause a rash, itching, redness, or other discoloration of the skin, or a severe sunburn. Use a sunscreen when you are outdoors. Avoid sunlamps and tanning beds.

Serious skin reactions, including Stevens-Johnson syndrome, toxic epidermal necrolysis, and drug reaction with eosinophilia and systemic symptoms (DRESS) can occur with this medicine. Check with your doctor right away if you have black, tarry stools, blistering, peeling, or loosening of the skin, chest pain, chills, cough, diarrhea, fever, itching, painful or difficult urination, red irritated eyes, red skin lesions, severe acne or skin rash, sore throat, sores or ulcers or white spots in the mouth or on the lips, swollen glands, or unusual tiredness or weakness while you are using this medicine.

Before you have any medical tests or x-rays, tell the medical doctor in charge that you are using this medicine. The results of some tests may be affected by this medicine.

You should not drink alcoholic beverages or take other alcohol-containing preparations while you are using this medicine, and for at least 1 day after stopping it.

If your symptoms do not improve within a few days or if they become worse, check with your doctor.

Do not take other medicines unless they have been discussed with your doctor. This includes prescription or nonprescription (over-the-counter [OTC]) medicines and herbal or vitamin supplements.

Serious side effects

Along with its needed effects, bismuth subcitrate potassium / 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 subcitrate potassium / metronidazole / tetracycline:

Other side effects

Some side effects of bismuth subcitrate potassium / 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:

For healthcare professionals

Applies to bismuth subcitrate potassium / metronidazole / tetracycline: oral capsule.

General adverse events

The most commonly reported side effects included abnormal feces, nausea, and diarrhea.^[Ref]

Gastrointestinal

• Very common (10% or more): Abnormal feces (up to 15.6%)
• Common (1% to 10%): Nausea, diarrhea, abdominal pain, dyspepsia, constipation, dry mouth
• Frequency not reported: Flatulence, glossitis, vomiting, tongue darkening, gastritis, gastroenteritis, duodenal ulcer
• Postmarketing reports: Abdominal distention, eructation, flatulence, pseudomembranous colitis/Clostridium difficile colitis

Metronidazole:

• Frequency not reported: Nausea, vomiting, diarrhea, abdominal pain, constipation, furry tongue, glossitis, stomatitis, dry mouth, pancreatitis

Tetracycline:

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

Nervous system

• Common (1% to 10%): Headache, dysgeusia, dizziness
• Frequency not reported: Somnolence
• Postmarketing reports: Peripheral neuropathy

Metronidazole:

• Frequency not reported: Metallic taste, convulsive seizures, encephalopathy, aseptic meningitis, peripheral neuropathy, headache, syncope, dizziness, vertigo, incoordination, ataxia, dysarthria

Tetracycline:

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

Other

• Common (1% to 10%): Asthenia, abnormal laboratory tests
• Frequency not reported: Malaise
• Postmarketing reports: Fatigue, candidiasis

Metronidazole:

• Frequency not reported: Candida overgrowth, fever, weakness

Tetracycline:

• Frequency not reported: Tinnitus^[Ref]

Genitourinary

• Common (1% to 10%): Vaginal infection, urine abnormality

Metronidazole:

• Frequency not reported: Vaginal/vulvar dryness, dysuria, polyuria, incontinence, darkened urine, pelvic pressure, dyspareunia, proctitis^[Ref]

Hepatic

• Common (1% to 10%): ALT increase, AST increase

Tetracycline:

• Frequency not reported: Hepatotoxicity, liver failure^[Ref]

Dermatologic

• Common (1% to 10%): Maculopapular rash
• Uncommon (0.1% to 1%): Rash
• Frequency not reported: Pruritus
• Postmarketing reports: Stevens-Johnson syndrome, toxic epidermal necrolysis, drug rash with eosinophilia and systemic symptoms (DRESS)

Metronidazole:

• Frequency not reported: Urticaria, erythematous rash, pruritus

Tetracycline:

• Frequency not reported: Maculopapular/erythematous rash, onycholysis, nail discoloration, exfoliative dermatitis, photosensitivity, urticaria, Henoch-Schonlein purpura, systemic lupus erythematosus exacerbation^[Ref]

Cardiovascular

• Frequency not reported: Chest pain, tachycardia
• Postmarketing reports: Chest discomfort

Metronidazole:

• Frequency not reported: T-wave flattening, flushing

Tetracycline:

• Frequency not reported: Pericarditis^[Ref]

Metabolic

• Frequency not reported: Increased appetite, increased weight

Metronidazole:

• Frequency not reported: Anorexia

Tetracycline:

• Frequency not reported: Anorexia^[Ref]

Musculoskeletal

• Frequency not reported: Back pain, increased blood creatinine phosphokinase, myalgia

Metronidazole:

• Frequency not reported: Joint pain

Tetracycline:

• Frequency not reported: Myasthenic syndrome^[Ref]

Ocular

• Frequency not reported: Visual disturbance

Metronidazole:

• Frequency not reported: Optic neuropathy^[Ref]

Hematologic

Metronidazole:

• Frequency not reported: Reversible neutropenia/leukopenia, reversible thrombocytopenia

Tetracycline:

• Frequency not reported: Hemolytic anemia, thrombocytopenia, thrombocytopenic purpura, neutropenia, eosinophilia

Renal

Metronidazole:

• Frequency not reported: Cystitis

Tetracycline:

• Frequency not reported: Increased blood urea nitrogen

Psychiatric

• Frequency not reported: Anxiety

Metronidazole:

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

Hypersensitivity

Tetracycline:

• Frequency not reported: Angioedema, anaphylaxis^[Ref]

Immunologic

Tetracycline:

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

Respiratory

Metronidazole:

• Frequency not reported: Nasal congestion^[Ref]

See also:

Further information

Bismuth subcitrate potassium/metronidazole/tetracycline side effects can vary depending on the individual. Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

Note: Medication side effects may be underreported. If you are experiencing side effects that are not listed, submit a report to the FDA by following this guide.

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