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

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

• headache
• tiredness
• vomiting

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:

• muscle aches
• rash
• signs of Depression (e.g., poor concentration, changes in weight, changes in sleep, decreased interest in activities, thoughts of suicide)
• signs of a slow heartbeat (e.g., dizziness, fainting, fatigue, shortness of breath, chest pain)

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 Epclusa.

Each pink, diamond-shaped, film-coated tablet debossed with "GSI" on one side and "7916" on the other contains 400 mg of sofosbuvir and 100 mg of velpatasvir. Nonmedicinal ingredients: copovidone, croscarmellose sodium, magnesium stearate, and microcrystalline cellulose; film coating: iron oxide red, polyethylene glycol, polyvinyl alcohol, talc, and titanium dioxide.

Do not take Epclusa if you are allergic to sofosbuvir, velpatasvir, or any ingredients of the medication.

There may be an interaction between sofosbuvir - velpatasvir and any of the following:

• Aliskiren
• Amiodarone
• antacids (e.g., aluminum hydroxide, calcium carbonate, magnesium hydroxide)
• anticancer medications (e.g., Doxorubicin, Etoposide, Paclitaxel, Vincristine)
• Apalutamide
• bilastine
• Bosentan
• Colchicine
• Cyclosporine
• dabigatran
• Deferasirox
• Diabetes medications (e.g., Canagliflozin, Glyburide, insulin, Linagliptin, Liraglutide, Metformin, Rosiglitazone)
• Digoxin
• Edoxaban
• Elagolix
• Eliglustat
• Enzalutamide
• Everolimus
• H2 antagonists (e.g., Famotidine, Ranitidine)
• hepatitis C antivirals (e.g., glecaprevir and pibrentasvir, grazoprevir, ledipasvir, voxilaprevir)
• HIV non-nucleoside reverse transcriptase inhibitors (NNRTIs; e.g., efavirenz, etravirine, nevirapine)
• HIV protease inhibitors (e.g., ritonavir, tipranavir)
• lumacaftor and Ivacaftor
• Modafinil
• Morphine
• Nadolol
• Naloxegol
• proton pump inhibitors (e.g., Lansoprazole, Omeprazole)
• rifabutin
• rifampin
• rifaximin
• Risperidone
• Romidepsin
• Sarilumab
• seizure medications (e.g., Carbamazepine, Clobazam, Levetiracetam, Phenobarbital, Phenytoin, primidone, Topiramate, Valproic acid, zonisamide)
• St. John's wort
• Silodosin
• siltuximab
• Sirolimus
• "statin" anti-cholesterol medications (e.g., Atorvastatin, Lovastatin, Rosuvastatin, Simvastatin)
• Tacrolimus
• Tocilizumab
• Tolvaptan
• tyrosine kinase inhibitors (e.g., Bosutinib, Crizotinib, Dabrafenib, imatinib, Lapatinib, Nilotinib)
• Warfarin

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 Epclusa. 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 Epclusa.

Hepatitis B co-infection: Talk to your doctor before taking Epclusa if you have or have had hepatitis B. People with hepatitis B infection that is dormant may experience a recurrence of the hepatitis B while they are taking sofosbuvir – velpatasvir or after they stop taking Epclusa. This can result in severe liver damage and possibly life-threatening liver failure. If you experience symptoms of worsening liver function, such as fatigue, feeling unwell, loss of appetite, nausea, yellowing of the skin or whites of the eyes, dark urine, pale stools, abdominal pain or swelling, and itchy skin, contact your doctor immediately.

Human immunodeficiency virus (HIV) co-infection: Sofosbuvir - velpatasvir has been found to be a safe and effective treatment for hepatitis C, for people who also have HIV infection. Some of the medications used to treat HIV infection may affect sofosbuvir or velpatasvir and change how these medications work in the body. If you have HIV infection, discuss with your doctor how Epclusa may affect your medical condition, how your medical condition may affect the dosing and effectiveness of Epclusa, and whether any special monitoring is needed.

Liver transplant: The safety and effectiveness of using sofosbuvir - velpatasvir after having a liver transplant have not been determined. Epclusa is not recommended for anyone who has had a liver transplant.

Pregnancy and contraception: The use of Epclusa is not recommended for pregnant women or women who may become pregnant, as it is not known if sofosbuvir - velpatasvir will harm an unborn child. If you become pregnant while taking Epclusa, contact your doctor immediately.

If you are using ribavirin along with sofosbuvir - velpatasvir, you must use 2 forms of effective birth control (one for each partner) during treatment and for 6 months after stopping the medication. During this time, women will have monthly pregnancy tests to ensure they are not pregnant. Tell your doctor immediately if you become pregnant while using Epclusa.

Breast-feeding: It is not known if sofosbuvir or velpatasvir pass into breast milk. If you are breast-feeding and are taking Epclusa, it may affect your baby. Talk to your doctor about whether you should continue breast-feeding.

Children: The safety and effectiveness of using Epclusa have not been established for children less than 12 years of age or who weigh less than 30kg. Epclusa has not been studied for children with moderate or severe liver impairment.