Tybost Side Effects

Generic name: cobicistat

Medically reviewed by Drugs.com. Last updated on Mar 30, 2025.

Note: This document provides detailed information about Tybost.

Applies to cobicistat: oral tablet Side Effects associated with cobicistat. Some dosage forms listed on this page may not apply specifically to the brand name Tybost.

Applies to cobicistat: oral tablet.

Precautions

Your doctor will want to check your progress at regular visits, especially during the first few weeks that you take this medicine. Blood and urine tests may be needed to check for any unwanted effects.

This medicine should not be used together with atazanavir or darunavir if you are also using any of the following: alfuzosin (Uroxatral®), carbamazepine (Tegretol®), colchicine (Colcrys®), dronedarone (Multaq®), drospirenone/ethinyl estradiol (Yasmin®, Yaz®), indinavir (Crixivan®), irinotecan (Camptosar®), lomitapide (Juxtapid®), lovastatin (Altoprev®, Mevacor®), lurasidone (Latuda®), midazolam (Versed®), nevirapine (Viramune®), phenobarbital (Luminal®), phenytoin (Dilantin®), pimozide (Orap®), ranolazine (Ranexa®), rifampin (Rifadin®), sildenafil (Revatio®), simvastatin (Simcor®, Zocor®), St John's wort, triazolam (Halcion®), or ergot medicines (eg, dihydroergotamine, ergotamine, methylergonovine, Cafergot®, Migranal®). Doing so may cause serious unwanted effects.

Using this medicine while you are pregnant can harm your unborn baby. Use an effective form of birth control to keep from getting pregnant during treatment with this medicine. Certain birth control pills may not work as well to prevent pregnancy when used with this medicine. Use another form of birth control (eg, condoms, spermicide) along with your pills. If you think you have become pregnant while using this medicine, tell your doctor right away.

Using this medicine together with tenofovir DF may cause kidney problems (including Fanconi syndrome). Tell your doctor right away if you have bloody urine, decreased frequency or amount of urine, increased thirst, loss of appetite, lower back or side pain, nausea, vomiting, swelling of the face, fingers, or lower legs, trouble breathing, unusual tiredness or weakness, or weight gain.

This medicine does not decrease the risk of transmitting the HIV infection to others through sexual contact or by contaminated blood. Make sure you understand and practice safe sex, even if your partner also has HIV. Avoid sharing needles with anyone.

Do not take other medicines unless they have been discussed with your doctor. This includes prescription or nonprescription (over-the-counter [OTC]) medicines and herbal or vitamin supplements.

Serious side effects of Tybost

Along with its needed effects, cobicistat (the active ingredient contained in Tybost) may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

Check with your doctor immediately if any of the following side effects occur while taking cobicistat:

Other side effects of Tybost

Some side effects of cobicistat may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects.

Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:

For healthcare professionals

Applies to cobicistat: oral tablet.

General adverse events

In a clinical trial, safety of this drug was evaluated in therapy-naive patients using cobicistat-boosted atazanavir with emtricitabine-tenofovir disoproxil fumarate (DF). The most common side effects were jaundice and rash; side effects associated with elevated bilirubin levels were frequently reported.

The manufacturer product information for atazanavir or darunavir should be consulted.^[Ref]

Hepatic

• Very common (10% or more): Hyperbilirubinemia, increased total bilirubin, jaundice, increased ALT or AST
• Common (1% to 10%): Increased ALT, increased AST, increased GGT^[Ref]

In 1 clinical trial, hyperbilirubinemia (greater than 1 times the upper limit of normal [1 x ULN]) was reported in 97.7% of patients in the cobicistat-boosted atazanavir group and 97.4% in the ritonavir-boosted atazanavir group through 144 weeks of therapy. Increases in total bilirubin greater than 2 x ULN was reported in 88% of patients in the cobicistat-boosted group and 80.9% in the ritonavir-boosted group. Increases in total bilirubin greater than 2.5 x ULN was reported in 73% of patients in the cobicistat-boosted group and 66% in the ritonavir-boosted group. Increased ALT or AST (greater than 3 x ULN) was reported in 12.8% of patients in the cobicistat-boosted group and 9% in the ritonavir-boosted group. Increased ALT (greater than 5 x ULN), AST (greater than 5 x ULN), and GGT (greater than 5 x ULN) were reported in 6%, 4%, and 4% of patients in the cobicistat-boosted group, respectively.^[Ref]

Ocular

• Very common (10% or more): Ocular icterus^[Ref]

Gastrointestinal

• Very common (10% or more): Nausea
• Common (1% to 10%): Vomiting, diarrhea, dyspepsia, abdominal pain, abdominal distension, flatulence, dry mouth, increased lipase, increased serum amylase
• Frequency not reported: Upper abdominal pain^[Ref]

Increased serum amylase (greater than 2 x ULN) was reported in up to 4% of patients in the cobicistat-boosted group.

If serum amylase was greater than 1.5 x ULN, lipase was also measured. Increased lipase (grades 3 to 4) was reported in up to 7% of patients in the cobicistat-boosted group.^[Ref]

Musculoskeletal

• Common (1% to 10%): Increased creatine kinase, back pain
• Uncommon (0.1% to 1%): Myalgia
• Frequency not reported: Rhabdomyolysis^[Ref]

Increased creatine kinase (at least 10 x ULN) was reported in up to 8% of patients in the cobicistat-boosted group.^[Ref]

Genitourinary

• Common (1% to 10%): Hematuria (increased urine RBC), glycosuria (increased urine glucose)
• Uncommon (0.1% to 1%): Proteinuria^[Ref]

Increased urine RBC (greater than 75 RBC/high power field) and urine glucose (at least 1000 mg/dL) have been reported in up to 6% and 3% of patients in the cobicistat-boosted group, respectively.^[Ref]

Hematologic

• Common (1% to 10%): Decreased neutrophils

Decreased neutrophils (less than 750/mm3) has been reported in up to 3% of patients in the cobicistat-boosted group.

Nervous system

• Common (1% to 10%): Headache, dizziness, somnolence, dysgeusia^[Ref]

Metabolic

• Common (1% to 10%): Hyperglycemia/increased serum glucose, increased appetite^[Ref]

Increased serum glucose (greater than 250 mg/dL) has been reported in up to 2% of patients in the cobicistat-boosted group.^[Ref]

Other

• Common (1% to 10%): Fatigue
• Uncommon (0.1% to 1%): Pyrexia, asthenia
• Frequency not reported: Increased fasted total cholesterol, increased fasted high-density lipoprotein cholesterol, increased fasted low-density lipoprotein cholesterol, increased fasted triglycerides^[Ref]

Psychiatric

• Common (1% to 10%): Insomnia, abnormal dreams, depression
• Uncommon (0.1% to 1%): Sleep disorder^[Ref]

Dermatologic

• Common (1% to 10%): Rash (rash events included allergic dermatitis, drug hypersensitivity, generalized pruritus, eosinophilic pustular folliculitis, rash, generalized rash, macular rash, maculopapular rash, morbilliform rash, papular rash, urticaria)
• Uncommon (0.1% to 1%): Pruritus^[Ref]

Respiratory

• Common (1% to 10%): Influenza, bronchitis, upper respiratory tract infection, nasopharyngitis

Renal

• Uncommon (0.1% to 1%): Nephrolithiasis
• Frequency not reported: Decreased estimated CrCl, increased serum creatinine, tubular secretion of creatinine inhibited (actual renal glomerular function not affected), decreased estimated glomerular filtration rate (eGFR), renal impairment (including acute renal failure, Fanconi syndrome), nephropathy, Fanconi syndrome acquired^[Ref]

In 1 trial, increased serum creatinine and decreased estimated CrCl occurred early in treatment with this drug, after which they stabilized. The mean change in eGFR (by Cockcroft-Gault method) after 144 weeks of therapy was -15.1 mL/min in the cobicistat-boosted group.

In HIV-1-infected therapy-experienced patients with mild to moderate renal dysfunction (eGFR [by Cockcroft-Gault method) 50 to 89 mL/min) who switched pharmacokinetic enhancer from ritonavir to cobicistat (the active ingredient contained in Tybost) the mean change in serum creatinine was 0.07 mg/dL and the mean change in eGFR (by Cockcroft-Gault method) was -6.2 mL/min at week 96.

Renal impairment (including acute renal failure and Fanconi syndrome) has been reported when this drug was used in regimen containing tenofovir DF.^[Ref]

See also:

Frequently asked questions

• What drugs are contained in the HIV treatment Symtuza?
• Genvoya vs Stribild for HIV - How do they compare?

Further information

Tybost side effects can vary depending on the individual. Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

Note: Medication side effects may be underreported. If you are experiencing side effects that are not listed, submit a report to the FDA by following this guide.

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