Many medications can cause side effects. A side effect is an unwanted response to a medication when it is taken in normal doses. Side effects can be mild or severe, temporary or permanent.

The side effects listed below are not experienced by everyone who takes Incivek. If you are concerned about side effects, discuss the risks and benefits of Incivek with your doctor.

The following side effects have been reported by at least 1% of people taking Incivek. Many of these side effects can be managed, and some may go away on their own over time.

Contact your doctor if you experience these side effects and they are severe or bothersome. Your pharmacist may be able to advise you on managing side effects.

• burning or itching around the anus
• change in taste sensation
• Diarrhea
• hemorrhoids
• itchiness
• nausea
• vomiting

Although most of the side effects listed below don't happen very often, they could lead to serious problems if you do not check with your doctor or seek medical attention.

Check with your doctor as soon as possible if any of the following side effects occur:

• fainting
• mild to moderate rash
• signs of Anemia (low red blood cells; e.g., dizziness, pale skin, unusual tiredness or weakness, shortness of breath)

Stop taking the medication and seek immediate medical attention if any of the following occur:

• signs of a severe skin reaction such as blistering, peeling, ulcers, rash covering a large area of the body, a rash that spreads quickly, or a rash combined with Fever
• skin rash that gets worse

Some people may experience side effects other than those listed. Check with your doctor if you notice any symptom that worries you while you are taking Incivek.

Each purple, film-coated, capsule-shaped tablet, debossed with "V 375" on one side, contains telaprevir 375 mg. Nonmedicinal ingredients: colloidal silicon dioxide, croscarmellose sodium, D&C Red No. 40, dibasic calcium phosphate (anhydrous), FD&C Blue No. 2, hypromellose acetate succinate, microcrystalline cellulose, polyethylene glycol, polyvinyl alcohol, sodium lauryl sulfate, sodium stearyl fumarate, talc, and titanium dioxide.

Do not take telaprevir if you:

• are allergic to telaprevir or any ingredients of the medication
• are pregnant or your female partner is pregnant
• are unable to take peginterferon alfa or ribavirin
• are taking any of the following medications:
• Alfuzosin
• Amiodarone
• Carbamazepine
• cisapride
• Eplerenone
• ergot derivatives (e.g., Dihydroergotamine, ergotamine)
• Flecainide
• Pimozide
• Propafenone
• quinidine
• rifampin
• Sildenafil
• "statin" cholesterol-lowering medications (e.g., Atorvastatin, Lovastatin, Simvastatin)
• St. John's wort
• Triazolam
• "triptan" medications (e.g., Eletriptan)
• Vardenafil

There may be an interaction between telaprevir and any of the following:

If you are taking any of these medications, speak with your doctor or pharmacist. Depending on your specific circumstances, your doctor may want you to:

• stop taking one of the medications,
• change one of the medications to another,
• change how you are taking one or both of the medications, or
• leave everything as is.

An interaction between two medications does not always mean that you must stop taking one of them. Speak to your doctor about how any drug interactions are being managed or should be managed.

Medications other than those listed above may interact with Incivek. Tell your doctor or prescriber about all prescription, over-the-counter (non-prescription), and herbal medications you are taking. Also tell them about any supplements you take. Since caffeine, alcohol, the Nicotine from cigarettes, or street drugs can affect the action of many medications, you should let your prescriber know if you use them.

Before you begin using a medication, be sure to inform your doctor of any medical conditions or Allergies you may have, any medications you are taking, whether you are pregnant or breast-feeding, and any other significant facts about your health. These factors may affect how you should use Incivek.

Abnormal heart rhythms: Incivek can cause abnormal heart rhythms. Certain medications (e.g., Sotalol, quinidine, thioridazine, Chlorpromazine, droperidol, pimozide, gatifloxacin, moxifloxacin, Mefloquine, pentamidine, Dolasetron, Tacrolimus) can increase the risk of a type of an abnormal heart rhythm called QT prolongation, and should not be used in combination with telaprevir. You are more at risk for this type of abnormal heart rhythm and its complications if you:

• are female
• are older than 65 years of age
• have a family history of sudden cardiac death
• have a history of heart disease or abnormal heart rhythms
• have a slow heart rate
• have congenital prolongation of the QT interval
• have Diabetes
• have had a Stroke
• have low potassium, magnesium, or calcium levels
• have nutritional deficiencies

If you have heart disease, an abnormal heart rhythm, or are taking certain medications that may increase your risk of QT prolongation, discuss with your doctor how Incivek may affect your medical condition, how your medical condition may affect the dosing and effectiveness of Incivek, and whether any special monitoring is needed.

Anemia: Telaprevir may cause low levels of red blood cells, a condition called anemia. If you experience symptoms of anemia, such as dizziness, shortness of breath, feeling unusually tired, or pale skin, contact your doctor as soon as possible.

Your doctor will do blood tests regularly to monitor the number of specific types of blood cells, including red blood cells, in your blood.

Birth Control: Telaprevir must be used with ribavirin and peginterferon alfa. Treatment with ribavirin can cause severe birth defects to an unborn child. Both partners should use a reliable form of birth control while taking Incivek and for 6 months afterwards (the time it takes for ribavirin to be cleared from the body). For women, your doctor will not give you telaprevir until you have had a negative pregnancy test. Your doctor should have you continue to do monthly pregnancy tests to ensure that you do not become pregnant while using Incivek.

Methods of birth control that use hormones, such as a birth control pill, patch or injection, may not be fully reliable as telaprevir interacts with many medications and may change the way that your body uses the hormones. At least 2 forms of non-hormonal birth control (condom, diaphragm) must be used while you are taking Incivek.

Infection with HIV or hepatitis B: The safety and effectiveness of treatment with telaprevir have not been established for people who also have human immunodeficiency virus (HIV) or hepatitis B virus (HBV).

Kidney function: The safety and effectiveness of using telaprevir have not been established for people with severely reduced kidney function. If you have decreased kidney function, discuss with your doctor how Incivek may affect your medical condition, how your medical condition may affect the dosing and effectiveness of Incivek, and whether any special monitoring is needed.

Liver function: Telaprevir is not recommended for people with active, worsening liver disease, or moderate to severely reduced liver function. If you have a history of reduced liver function, discuss with your doctor how Incivek may affect your medical condition, how your medical condition may affect the dosing and effectiveness of Incivek, and whether any special monitoring is needed.

Organ Transplantation: The safety and effectiveness of treatment with telaprevir have not been established for people with liver or other organ transplants. Telaprevir may interact with medications used to prevent rejection of the transplanted organ.

Skin reactions: Telaprevir may cause skin rash or itchiness with or without a rash. Rarely, people taking telaprevir experience a severe skin reaction that can be life-threatening. If you experience mouth sores or ulcers, red or inflamed eyes (such as "pink eye"), a rash that gets worse, or develops into blisters, covers a large area of the body, or is associated with a fever, get immediate medical attention.

Pregnancy: Telaprevir has not been studied for use by pregnant women and it must be taken with peginterferon alfa and ribavirin. Ribavirin has been shown to cause serious problems in the developing fetus. As a result, telaprevir (plus peginterferon alfa and ribavirin) should not be used by pregnant women or by men whose partners are pregnant. Both partners should use a reliable form of birth control while taking Incivek and for 6 months afterwards. Tell your doctor immediately if you become pregnant while using Incivek.

Breast-feeding: It is not known if telaprevir passes into breast milk. If you are a breast-feeding mother and are taking Incivek, it may affect your baby. Talk to your doctor about whether you should continue breast-feeding.

Children and adolescents: The safety and effectiveness of using Incivek have not been established for children and adolescents less than 18 years of age.

Seniors: Seniors may be more likely to experience side effects when taking telaprevir.