Skip to main content


Generic name: bismuth subsalicylate, metronidazole, and tetracyclineBIZ-muth-sub-sa-LISS-i-late, MET-roe-NYE-da-zole, and-tet-ra-SYE-kleen ]
Drug class: H. pylori eradication agents

Medically reviewed by on Sep 4, 2023. Written by Cerner Multum.

What is Helidac (Helidac)?

Bismuth subsalicylate potassium, metronidazole, and tetracycline (Helidac) is a combination medicine used to treat peptic ulcer (duodenal ulcer) with Helicobacter pylori infection. Helidac is usually given together with another medicine to reduce stomach acid.

Helidac may also be used for purposes not listed in this medication guide.

Helidac side effects

Stop taking Helidac and get emergency medical help if you have signs of an allergic reaction (hives, difficult breathing, swelling in your face or throat) or a severe skin reaction (fever, sore throat, burning eyes, skin pain, red or purple skin rash with blistering and peeling).

Helidac may cause serious side effects. Call your doctor at once if you have:

  • severe stomach pain, diarrhea that is watery or bloody (even if it occurs months after your last dose);

  • dizziness, problems with speech or coordination;

  • fever, neck stiffness, increased sensitivity to light, nausea, vomiting.

  • a seizure;

  • vaginal itching or discharge;

  • numbness or tingling in your arms and legs; or

  • increased pressure inside the skull--severe headaches, ringing in your ears, dizziness, nausea, vision problems, pain behind your eyes.

Helidac may cause your tongue to become darker in color. It may also cause your stools to appear black in color. These are harmless and temporary side effects.

Common side effects of Helidac may include:

  • stomach pain, nausea, diarrhea;

  • dark-colored stools;

  • mouth sores; or

  • swollen tongue, black or "hairy" tongue.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.


Do not drink alcohol or consume foods or medicines that contain propylene glycol while you are taking Helidac and for at least 3 days after you stop taking it.

Metronidazole has caused cancer in animal studies. It is not known whether this would occur in humans taking Helidac.

Before taking this medicine

You should not use Helidac if you are allergic to bismuth subsalicylate potassium, metronidazole, or tetracycline, or if:

  • you have severe kidney disease;

  • you drink alcohol daily;

  • you regularly consume foods or medicines that contain propylene glycol;

  • you took disulfiram (Antabuse) within the past 14 days;

  • you also use methoxyflurane; or

  • you are allergic to aspirin.

Tell your doctor if you have ever had:

Metronidazole has caused cancer in animal studies. It is not known whether this would occur in humans taking Helidac. Ask your doctor about the risk.

Do not use Helidac if you are pregnant. Tetracycline can cause permanent tooth discoloration and affect growth in the baby. Tell your doctor if you become pregnant.

Helidac can make birth control pills less effective. Ask your doctor about other birth control options such as an injection, implant, skin patch, vaginal ring, condom, diaphragm, cervical cap, or contraceptive sponge.

You should not breastfeed within 24 hours after using Helidac. If you use a breast pump during this time, throw out any milk you collect. Do not feed it to your baby.

Not approved for use by anyone younger than 18 years old.

How should I take Helidac?

Follow all directions on your prescription label and read all medication guides or instruction sheets. Use the medicine exactly as directed.

Chew and swallow the bismuth subsalicylate tablets.

Do not chew the metronidazole or tetracycline pills. Swallow each pill whole.

Take each dose (especially the bedtime dose) with a full glass of water (8 ounces). Do not take with milk.

Take all 4 pills four times daily with meals and at bedtime.

Keep using Helidac even if your symptoms quickly improve. Skipping doses could make your infection resistant to medication. Helidac will not treat a viral infection (flu or a common cold).

Bismuth can affect the results of certain x-rays or medical tests. Tell any doctor who treats you that you are using Helidac.

Store at room temperature away from moisture and heat.

What happens if I miss a dose?

Take the medicine as soon as you can, but skip the missed dose if it is almost time for your next dose. Do not take two doses at one time.

If you miss more than 4 doses in a row, call your doctor for instructions.

What happens if I overdose?

Seek emergency medical attention or call the Poison Help line at 1-800-222-1222.

Overdose symptoms may include severe weakness, confusion, balance problems, nausea, vomiting, diarrhea, high fever, ringing in your ears, numbness or tingling, fast heartbeats, rapid or difficult breathing, seizure, or coma.

What should I avoid while taking Helidac?

While taking Helidac and for 3 days after your last dose: Do not drink alcohol or consume foods, medicines, or other products that contain alcohol or propylene glycol. You may have unpleasant effects such as headaches, nausea, vomiting, stomach cramps, and warmth or tingling under your skin.

Avoid taking Helidac at the same time you consume milk or other dairy products, or take multivitamins, mineral supplements, or antacids. These products can make it harder for your body to absorb the medicine.

Antibiotic medicines can cause diarrhea. Tell your doctor if you have diarrhea that is watery or bloody.

Helidac could make you sunburn more easily. Avoid sunlight or tanning beds. Wear protective clothing and use sunscreen (SPF 30 or higher) when you are outdoors.

What other drugs will affect Helidac?

Tell your doctor about all your current medicines. Many drugs can affect Helidac, especially:

  • aspirin;

  • cimetidine;

  • probenecid;

  • an antidepressant;

  • asthma medication;

  • busulfan or other cancer medicine;

  • diabetes medication;

  • heart or blood pressure medication;

  • lithium or other antipsychotic medicine;

  • medicine to treat malaria, HIV, or other infection;

  • a blood thinner--warfarin, Coumadin, Jantoven; or

  • seizure medicine--phenytoin or phenobarbital.

This list is not complete and many other drugs may affect Helidac. This includes prescription and over-the-counter medicines, vitamins, and herbal products. Not all possible drug interactions are listed here.

Further information

Remember, keep this and all other medicines out of the reach of children, never share your medicines with others, and use this medication only for the indication prescribed.

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