The most common side effects of Harvoni are

In most cases these side effects are mild or moderate.

Drug interactions

Always consult your doctor and pharmacist about all the other prescription and non-prescription drugs you are taking, including methadone or other opiate substitution therapies, herbs, supplements and street drugs.

Drug interactions occur when one medication affects how another is absorbed, used or flushed out of the body. Some drugs can interact with Harvoni, increasing or decreasing the level of one or both drugs in the body. Increased levels can lead to new or more severe side effects. Decreased levels may mean that the drug won’t be as effective.

This is not a complete list of possible drug interactions with Harvoni.

It is not recommended to take Harvoni with the following medications:

medication to treat irregular heartbeat, such as amiodarone
cholesterol-lowering medication, such as rosuvastatin (Crestor)
anti-seizure medication, such as carbamazepine (Tegretol), phenobarbital, oxcarbazepine (Trileptal) and phenytoin (Dilantin)
some hepatitis C medications, such as simeprevir (Galexos)
tuberculosis medication, such as rifampin
any medicinal herbs, especially an herb used to treat depression – St. John’s wort (Hypericum perforatum), or hyperforin or hypericin, active ingredients in St. John’s wort
HIV medication, such as:
- Stribild (elvitegravir + cobicistat + emtricitabine + tenofovir);
- tipranavir (Aptivus) + ritonavir (Norvir)

When it is taken with the following medications it could potentially cause significant drug interactions:

antacids or buffered medications
HIV medication, such as:
- Atripla (efavirenz + emtricitabine + tenofovir);
- tenofovir (Viread and in Truvada) used together with atazanavir (Reyataz), darunavir (Prezista, Prezcobix) or Kaletra (lopinavir + ritonavir);
medication to treat indigestion, heartburn or ulcers, such as nizatidine (Axid), famotidine (Pepcid AC, Peptic Guard), ranitidine (Zantac), esomeprazole (Nexium), lansoprazole (Prevacid), omeprazole (Losec) and pantoprazole (Pantoloc)

Talk to your nurse, doctor and pharmacist if you are taking any of these medicines. One way to manage drug interactions is to make sure that your doctor and pharmacist know about everything you are taking, including prescription drugs, over-the-counter drugs, street drugs, herbal medications, supplements or anything else. If you have more than one doctor or pharmacist, it is possible for drug interactions to get missed. If more than one doctor is writing prescriptions for you, let each one know about everything you are taking. If possible, use the same pharmacy for all your prescriptions.