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 Pifeltro. If you are concerned about side effects, discuss the risks and benefits of Pifeltro with your doctor.

The following side effects have been reported by at least 1% of people taking Pifeltro. 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.

• Diarrhea
• dizziness
• drowsiness
• fatigue
• headache
• nausea
• stomach pain
• trouble sleeping
• unusual dreams
• vomiting
• weakness

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

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

• signs of Depression (e.g., poor concentration, changes in weight, changes in sleep, decreased interest in activities, thoughts of suicide)
• symptoms of immune system changes (e.g., Fever, joint or muscle pain, redness, rash, swelling, or fatigue)

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

• signs of a serious allergic reaction (e.g., abdominal cramps, difficulty breathing, nausea and vomiting, or swelling of the face and throat)
• signs of a severe skin reaction such as blistering, peeling, a rash covering a large area of the body, a rash that spreads quickly, or a rash combined with fever or discomfort

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 Pifeltro.

Each white, oval-shaped, film-coated tablet, debossed with the corporate logo and "700" on one side, and plain on the other side, contains 100 mg of doravirine. Nonmedicinal ingredients: carnauba wax, colloidal silicon dioxide, croscarmellose sodium, hypromellose acetate succinate, lactose monohydrate, magnesium stearate, and microcrystalline cellulose; film coating: hypromellose, lactose monohydrate, titanium dioxide, and triacetin.

Do not take Pifeltro if you:

• are allergic to doravirine or any ingredients of the medication
• are taking any of the following medications:
• Carbamazepine
• Enzalutamide
• Mitotane
• Oxcarbazepine
• Phenobarbital
• Phenytoin
• rifampin
• rifapentine
• St. John's wort

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

• Apalutamide
• Bosentan
• Dabrafenib
• Deferasirox
• Dexamethasone
• Erdafitinib
• enzalutamide
• ergonovine
• other HIV non-nucleoside reverse transcriptase inhibitors (NNRTIs; e.g., efavirenz, etravirine, nevirapine)
• Ivacaftor
• lumacaftor
• Methadone
• mitotane
• Modafinil
• Orlistat
• rifabutin
• rifampin
• rilpivirine
• St. John's wort
• seizure medications (e.g., carbamazepine, oxcarbazepine, phenobarbital, phenytoin)
• Sarilumab
• siltuximab
• Tocilizumab
• Voriconazole

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 Pifeltro. 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 Pifeltro.

Blood sugar: Doravirine may cause an increase in blood sugar levels (may cause a loss of blood glucose control) and glucose tolerance may change. People with Diabetes may find it necessary to monitor their blood sugar more frequently while using Pifeltro.

If you have diabetes or are at risk for developing diabetes, discuss with your doctor how Pifeltro may affect your medical condition, how your medical condition may affect the dosing and effectiveness of Pifeltro, and whether any special monitoring is needed.

Cholesterol: Doravirine can cause increased blood cholesterol levels. If you are at risk of developing High Cholesterol or you have high cholesterol levels before starting doravirine, discuss with your doctor how Pifeltro may affect your medical condition, how your medical condition may affect the dosing and effectiveness of Pifeltro, and whether any special monitoring is needed.

Drowsiness/reduced alertness: Doravirine may cause drowsiness or dizziness, affecting your ability to drive or operate machinery. Avoid driving, operating machinery, or performing other potentially hazardous tasks until you have determined how you are affected by Pifeltro.

Immune reconstitution syndrome: Pifeltro may cause immune reconstitution syndrome, where signs and symptoms of inflammation from previous infections appear. These symptoms occur soon after starting anti-HIV medication and can vary. They are thought to occur as a result of the immune system improving and being able to fight infections that have been present without symptoms (such as pneumonia, herpes, or Tuberculosis). Report any new symptoms to your doctor immediately.

Stopping the medication: If you stop taking Pifeltro, your HIV infection could get worse. Take the medication exactly as prescribed by your doctor, and do not stop taking the medication without checking with your doctor first.

Pregnancy: Pifeltro should not be used during pregnancy unless the benefits outweigh the risks. If you become pregnant while taking Pifeltro, contact your doctor immediately.

Breast-feeding: It is not known if doravirine passes into breast milk. Women who have HIV infection should not breast-feed because of the risk of passing HIV to a baby who does not have the infection.

Children: The safety and effectiveness of using Pifeltro have not been established for children.