Amoxicillin is a penicillin antibiotic. Clarithromycin is a macrolide antibiotic. These antibiotics fight bacteria in the body.

Lansoprazole decreases the amount of acid produced in the stomach.

Prevpac is a combination medicine used in people with Helicobacter pylori (H. pylori) infection and stomach ulcers. Treating H. pylori infection can help prevent future stomach ulcers.

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

You should not take Prevpac if you've ever had a severe allergic reaction to certain antibiotics, if you've had certain heart rhythm disorders, or if you've had liver problems caused by taking clarithromycin.

Tell your doctor about all your current medicines and any you start or stop using. Many drugs can interact, and some drugs should not be used together.

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

Take Prevpac twice daily before you eat, unless your doctor tells you otherwise.

Swallow each pill whole and do not crush, chew, break, or open it.

Use this medicine for the full prescribed length of time, even if your symptoms quickly improve. Skipping doses can increase your risk of infection that is resistant to medication. This medicine will not treat a viral infection such as the flu or a common cold.

This medicine can affect the results of certain medical tests. Tell any doctor who treats you that you are using Prevpac.

Store at room temperature, away from moisture, heat, and light.

You should not take this medicine if you are allergic to amoxicillin (Amoxil), clarithromycin (Biaxin), or lansoprazole (Prevacid), or if:

• you have a history of long QT syndrome or certain heart rhythm disorders;

• you have ever had liver problems or jaundice caused by taking clarithromycin;

• you are allergic to azithromycin (Zithromax, Z-Pak), erythromycin, or telithromycin;

• you have had a severe allergic reaction to a penicillin antibiotic, including ampicillin, Augmentin, Principen, Timentin, Trimox, and others; or

• you have had a severe allergic reaction to a cephalosporin antibiotic such as cefdinir, cefprozil, cefuroxime, cephalexin, Duricef, Omnicef, Cefzil, Keflex, Spectracef, and others.

Some medicines can cause unwanted or dangerous effects when used with Prevpac. Your doctor may change your treatment plan if you also use:

• cisapride;

• colchicine (if you also have liver or kidney disease);

• dihydroergotamine or ergotamine;

• lovastatin (Advicor, Altoprev, Mevacor) or simvastatin (Zocor, Simcor, Vytorin, Juvisync); or

• pimozide.

Tell your doctor if you have ever had:

• liver disease;

• kidney disease;

• allergies;

• myasthenia gravis;

• osteoporosis or low bone mineral density (osteopenia); or

• an electrolyte imbalance or metabolic disorder.

You may be more likely to have a broken bone while taking this medicine long term or more than once per day. Talk with your doctor about ways to keep your bones healthy.

This medicine may harm an unborn baby. Use effective birth control to prevent pregnancy, and tell your doctor if you become pregnant.

Amoxicillin can make birth control pills less effective. Ask your doctor about using a non-hormonal birth control (condom, diaphragm with spermicide) to prevent pregnancy.

You should not breast-feed while using this medicine.

This medicine is not approved for use by anyone younger than 18 years old.

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.

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

Antibiotic medicines can cause diarrhea, which may be a sign of a new infection. If you have diarrhea that is watery or bloody, call your doctor before using anti-diarrhea medicine.

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).

Seek medical treatment if you have a serious drug reaction that can affect many parts of your body. Symptoms may include: skin rash, fever, swollen glands, muscle aches, severe weakness, unusual bruising, or yellowing of your skin or eyes.

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

• severe stomach pain, diarrhea that is watery or bloody;

• fast or pounding heartbeats, fluttering in your chest, shortness of breath, and sudden dizziness (like you might pass out);

• liver problems--upper stomach pain, itching, loss of appetite, dark urine, jaundice (yellowing of the skin or eyes);

• kidney problems--urinating more or less than usual, blood in your urine, swelling, rapid weight gain; or

• new or worsening symptoms of lupus--joint pain, and a skin rash on your cheeks or arms that worsens in sunlight.

Serious side effects may be more likely in older adults.

Common side effects of Prevpac may include:

• nausea, vomiting, diarrhea;

• headache;

• vaginal itching or discharge;

• unusual or unpleasant taste in the mouth; or

• 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.

If you take any of the following medicines, take them separately:

• Zidovudine: take Prevpac at least 2 hours before or 2 hours after you take Prevpac.

• Sucralfate (Carafate): take it at least 30 minutes after you take Prevpac.

Sometimes it is not safe to use certain medications at the same time. Some drugs can affect your blood levels of other drugs you take, which may increase side effects or make the medications less effective.

Clarithromycin can cause a serious heart problem. Your risk may be higher if you also use certain other medicines for infections, asthma, heart problems, high blood pressure, depression, mental illness, cancer, malaria, or HIV.

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

• antiviral medication;

• "statin" cholesterol medication;

• insulin or oral diabetes medicine (especially nateglinide, pioglitazone, repaglinide, or rosiglitazone);

• a blood thinner--warfarin (Coumadin, Jantoven);

• heart or blood pressure medication--amlodipine, diltiazem, verapamil; or

• a Valium-type sedative--alprazolam, midazolam, triazolam.

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