cobicistat COBI (PK booster)

Used only as a booster for other drugs; DHHS recommended as a component of initial regimen in certain clinical situations

Standard Dose

Used as a boosting agent (or PK enhancer) at a dose of 150 mg once a day with food taken at the same time with either Prezista 800 mg (co-formulated as Prezcobix), Reyataz 300 mg (co-formulated as Evotaz), or co-formulated in the single-tablet regimens Stribild, Genvoya, and Symtuza.

For adults and children weighing at least 77 pounds (if taken with atazanavir, brand name Reyataz) or at least 88 pounds (if taken with darunavir, brand name Prezista or in the single-tablet regimen Symtuza; anyone taking darunavir must be at least three years old). Tybost is not an HIV drug; it is a pharmacokinetic enhancer or a “booster” used to increase the levels of Prezista 800 mg once daily, Reyataz 300 mg once daily, or elvitegravir 150 mg in Stribild and Genvoya. Tybost is not interchangeable with Norvir when used to increase the levels of other HIV medications.

Take missed dose as soon as possible (at the same time as any separate medication prescribed) unless it’s closer to the time of your next dose. Tybost is not recommended for people with CrCl less than 70 mL/min when co-administered with a regimen containing TDF or for people with severe liver problems.
  • See package insert for more complete information on potential side effects and interactions.


Gilead Sciences, Inc.
gilead.com; tybost.com
(800) GILEAD-5 (445–3235)



Potential Side Effects and Toxicity

Potential Drug Interactions

More Information

Doctor Comments

Activist Comments