Viekira Pak (Viekira) is a combination antiviral medicine used to treat chronic hepatitis C virus (HCV) in adults. Viekira is sometimes given in combination with another antiviral medicine called ribavirin.

Viekira treats specific genotypes of hepatitis C, and only in certain people. Use only the medications prescribed for you. Do not share your medicine with other people.

Viekira is sometimes used in people who also have HIV. Viekira Pak is not a treatment for HIV or AIDS.

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

If you have ever had hepatitis B, Viekira can cause this condition to come back or get worse. You will need frequent blood tests to check your liver function.

Before you start taking Viekira, you must stop using certain birth control pills or hormone replacement medicines. Ask your doctor about using non-hormonal birth control to prevent pregnancy.

Your doctor will perform blood tests to make sure you do not have conditions that would prevent you from safely using Viekira.

Viekira is usually taken for 12 to 24 weeks. Follow all directions on your prescription label and read all medication guides or instruction sheets. Use the medicine exactly as directed.

Take this medicine with food.

Viekira XR is an extended-release form of this combination medicine to be taken once daily. Viekira XR is supplied as 3 pale yellow tablets that are taken all at once with a daily meal.

The Viekira Pak contains two different types of tablets. The pink tablet contains only ombitasvir, paritaprevir, and ritonavir. The beige tablet contains only dasabuvir.

Take 2 pink tablets plus 1 beige tablet at the same time every morning. Take 1 beige tablet at the same time every evening.

The monthly Viekira XR or Viekira Pak carton contains enough tablets for you to take this medicine for 4 weeks (28 days in a row).

You will need frequent blood tests to check your liver function.

If you have ever had hepatitis B, Viekira can cause this condition to come back or get worse. You will need liver function tests during treatment and for several months after you stop using this medicine.

You should not stop using Viekira suddenly. Stopping suddenly could make your hepatitis C harder to treat with antiviral medicine.

Use all medications as directed and read all medication guides you receive. Do not change your dose or dosing schedule without your doctor's advice. Every person with chronic hepatitis C should remain under the care of a doctor.

Store this medicine at room temperature away from moisture and heat. Do not remove the tablets from a daily dose package until you are ready to take the medicine.

You should not use Viekira if you are allergic to dasabuvir, ombitasvir, paritaprevir, or ritonavir, or if:

• you have moderate to severe liver disease; or

• you have ever had a severe skin rash after taking ritonavir (Norvir).

If you take Viekira with ribavirin: There may be other reasons you should not take this combination treatment. Tell your doctor about all your medical conditions.

Many drugs can interact and cause dangerous effects. Some drugs should not be used together with Viekira. Your doctor may change your treatment plan if you also use:

• alfuzosin;

• apalutamide;

• colchicine;

• dronedarone;

• efavirenz (Atripla, Sustiva, Symfi);

• ranolazine;

• rifampin;

• sildenafil (Revatio), when taken for pulmonary artery hypertension (PAH);

• St. John's wort;

• oral midazolam (Versed), or triazolam;

• anti-psychotic medicine--lurasidone, pimozide;

• birth control pills or patches--Lo Loestrin FE, Norinyl, Ortho Tri-Cyclen Lo, Ortho Evra, and others;

• hormone replacement therapy such as Fem HRT;

• a vaginal ring such as NuvaRing;

• cholesterol-lowering medicine--atorvastatin, gemfibrozil, lomitapide, lovastatin, simvastatin (Zocor, Vytorin, Simcor);

• an immunosuppressant--everolimus, sirolimus, tacrolimus;

• ergot medicine--dihydroergotamine, ergotamine, methylergonovine; or

• seizure medicine--carbamazepine, phenytoin, phenobarbital.

Before you start taking Viekira, you must stop using medicine that contains ethinyl estradiol. This includes certain birth control pills or hormone replacement medicines. Ask your doctor about using non-hormonal birth control (condom, diaphragm with spermicide) to prevent pregnancy while taking Viekira and for 2 weeks after your treatment ends.

Tell your doctor if you have ever had:

• liver problems other than hepatitis C (such as cirrhosis or hepatitis B);

• HIV (human immunodeficiency virus);

• a liver transplant; or

• if you use a blood thinner (warfarin, Coumadin, Jantoven) and you have routine "INR" or prothrombin time tests.

Viekira is sometimes used in combination with ribavirin. Both men and women using ribavirin should use effective birth control to prevent pregnancy. Ribavirin can cause birth defects, miscarriage, or death to an unborn baby if the mother or father is using this medicine.

You should not take ribavirin if you are pregnant, or if you are a man and your sex partner is pregnant. Use effective birth control to prevent pregnancy. Keep using birth control for at least 6 months after your last dose of ribavirin.

Tell your doctor right away if a pregnancy occurs while either the mother or the father is using ribavirin.

It may not be safe to breastfeed while using this medicine. Ask your doctor about any risk.

If you miss a dose of the pink tablets, take the missed dose with a meal as soon as you remember. If you are more than 12 hours late, skip the missed dose and take your next dose at the usual time with a meal.

If you forget to take the beige tablet, take it with a meal as soon as you remember. If you are more than 6 hours late in taking the beige tablet, skip the missed dose and take your next dose at the usual time with a meal.

Do not take two doses at one time.

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

Do not drink alcohol within 4 hours after you take Viekira XR.

Using this medicine will not prevent your disease from spreading. Do not have unprotected sex or share razors or toothbrushes. Talk with your doctor about safe ways to prevent HCV transmission during sex. Sharing drug or medicine needles is never safe, even for a healthy person.

Get emergency medical help if you have signs of an allergic reaction: hives; difficult breathing; swelling of your face, lips, tongue, or throat.

Call your doctor at once if you have new or worsening symptoms such as:

• confusion;

• loss of appetite, upper stomach pain;

• dark urine, clay-colored stools; or

• jaundice (yellowing of the skin or eyes).

Common side effects of Viekira Pak may include:

• nausea;

• itching, skin rash or redness;

• sleep problems (insomnia); or

• feeling weak or tired.

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.

When you start or stop taking Viekira, your doctor may need to adjust the doses of any other medicines you take on a regular basis.

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.

Many drugs can interact with Viekira, and some drugs should not be used together. This includes prescription and over-the-counter medicines, vitamins, and herbal products. Not all possible interactions are listed in this medication guide. Tell your doctor about all your current medicines and any medicine you start or stop using.