Atazanavir and Cobicistat (Oral)

Otherwise known by its brand name Evotaz, atazanavir and cobicistat is a combination of medicines that are used to treat and decrease the progression of illnesses that a HIV infection may cause.


When used as part of a treatment plan for human immunodeficiency virus (HIV), atazanavir and cobicistat treat HIV by helping to stop the infection from reproducing. This medicine will not have any effect on the contagiousness of HIV or AIDS and is predominantly used to delay the infection from spreading and destructing the immune system. Consequently, atazanavir and cobicistat can help to delay adverse effects that are related to AIDS or HIV but anyone receiving this medication is likely to have other problems related to the disease. For this reason, atazanavir and cobicistat should be used alongside other antiretroviral medicines, that have been planned by a health care professional who is experienced in the treatment of HIV and AIDS. It is also important to remember that atazanavir and cobicistat will not cure HIV infection or AIDS.

Atazanavir is an antiviral agent that works by stopping the virus-specific production of certain proteins that are found in HIV infected cells. Known as an azapeptide HIV-1 protease blocker, atazanavir prevents the formation of adult virions and the infection to new cells.

Cobicistat has no antiviral activity and works by enhancing the absorption, distribution, secretion and metabolism of atazanavir, ensuring that it can effectively fight the development of HIV cells. Atazanavir is negatively affected by certain cytochromes our bodies produce, that are dependent on our metabolism. One of these cytochromes is named CYP3A and particularly affects atazanavir, giving it a limited bioavailability and shortening its half-life. Cobicistat effectively inhibits these cytochromes, helping to enhance the effects of atazanavir.

HIV is a progressive and contagious virus that causes damage to the cells in your immune system. It decreases your ability to fight common infections and diseases that may be harmless to those who are uninfected. With a prolonged diagnosis or access to treatment, HIV can develop into AIDS, which is a number of life-threatening infections and illnesses that occur when the HIV virus has caused severe damage to your immune system.

There is currently no cure for HIV and AIDS, however, there are highly effective drug treatments that enable most people with the virus to live long, healthy lives. An early diagnosis and access to treatment also mean that most people with HIV will not progress into any AIDS-related illnesses and can live a relatively normal lifespan. When combined with other medications, atazanavir and cobicistat can contribute to a healthy life without AIDS. This medicine is orally taken in the form of tablets and should only ever be prescribed by a doctor, as part of a HIV treatment plan.

Conditions treated

  • Human immunodeficiency virus (HIV).

Type of medicine

  • Atazanavir is an antiretroviral agent. Cobicistat is a pharmacokinetic enhancer.

Side effects

Atazanavir and cobicistat are likely to cause side effects, with many of them being easy to maintain and manage with the help of your healthcare professional. It is important to maintain regular appointments and communication with your doctor to keep on track of any adverse effects that may be a result of your medication. When taking Atazanavir and cobicistat in combination with certain other medicines, it has the possibility to cause new or worse kidney problems, including kidney stones and kidney failure. For this reason, your doctor should check your kidneys before and during your treatment.

If you have any underlying illnesses or diseases, it is also vital to communicate this to your health care professional. Diabetes, haemophilia, hepatitis B, hepatitis C and any heart, liver or kidney problems are of particular importance as they may compromise the effects of atazanavir and cobicistat. If you do have any of the mentioned illnesses, your doctor will need to maintain extra appointments, tests and visits to ensure that your treatment and health will not be compromised.

For most patients taking this medication, the most common side effects tend to be stomach and taste related, taking the form of an accumulation of gas or fluid in the abdomen (abdominal distension), a distortion or lack of taste (dysgeusia), the accumulation of excess fat, and indigestion or stomach pain (dyspepsia). Many patients also experience problems with sleeping through insomnia, extreme drowsiness and tiredness.

Another common but more serious reaction to atazanavir and cobicistat is hyperbilirubinemia or jaundice. This is a condition caused by having too much bilirubin in the blood due to the breakdown of red blood cells. Symptoms of this include severe tenderness and pain in the abdomen, changes in mental function including agitation, drowsiness or confusion, blood or black, tarry stools, blood in vomit and a fever. You may also notice jaundice or a yellowing of the eyes (ocular icterus). If you happen to experience any of these symptoms, it is important that you contact your health care provider immediately as this could develop into a serious liver or gallbladder problem. For patients who have had elevated results on liver function tests or who may have a history of hepatitis B virus (HBV) or hepatitis C virus (HCV), may have an increased risk of developing new or deteriorating liver problems whilst taking this medication. In this scenario, it is likely that your doctor will perform liver function tests before and during your treatment.

If you notice any dizziness or lightheadedness whilst taking Atazanavir and cobicistat, it is essential that you inform your doctor immediately as it could be a sign of heart rhythm problems. As with all medications, there is also the rare possibility of an allergic reaction. If you experience any swelling and redness of the face and eyes, mouth sores, blisters, painful, warm or red lumps under your skin, muscle pain, a fever or a severe rash, go to your nearest hospital emergency room right away.

Uncommon side effects to this medication include an abnormal physical weakness or lethargy, muscle atrophy, a decrease in bile (cholestasis), hepatitis, inflammation of the stomach lining (gastritis), acute blistering and skin inflammation (erythema multiforme), a raised body temperature and a general feeling of discomfort or pain (malaise). If you experience any of these effects, it is important to consult your doctor right away.

In very rare cases, you may experience a disease of the muscle tissue known as myopathy, or a dilation of the blood vessels and decrease in blood pressure. If you experience chest pain, lack of sensory feeling, faintness, dark coloured urine or a fever, contact your doctor right away.


It is recommended that patients taking atazanavir and cobicistat take one tablet a day, orally and with food. This dose will be 300 mg atazanavir and 150 mg cobicistat.

If you miss a dose within 12 hours of your usual administration time, it is recommended that you take your prescribed dose as soon as possible and with food. If you miss a dose and it has been longer than 12 hours, this does should not be taken and instead, you should continue your usual dosing schedule when possible.

For patients with previous illnesses or diseases, your doctor is likely to maintain the standard dosage but will need clear communication and check-ups whilst on this treatment. Particular care should be taken for those with renal impairment and for anyone undergoing haemodialysis, this medication is not recommended.

The cobicistat in this medication has also been shown to lower creatinine clearance, making it unsuitable for patients with a creatinine clearance of less than 70 ml/min. For patients with mild hepatic impairment, atazanavir should be used with caution. It should not be used at all with patients who have moderate to severe hepatic impairment.


Before starting your atazanavir and cobicistat treatment it is essential that you inform your doctor of any other medications that you may be taking. For peace of mind, make sure to inform them of any herbal remedies, medicines or supplements that you are also taking, as these can interact with or alter the success of your medication. St John's Wort is a known contradictory herbal medicine to atazanavir and cobicistat, and must not be taken alongside the medicine.

Medicines that may seriously affect atazanavir and cobicistat include:

  • astemizole
  • cisapride
  • conivaptan
  • dihydroergotamine
  • ergotamine
  • flibanserin
  • ivabradine
  • lovastatin
  • midazolam
  • nevirapine
  • pitavastatin
  • sildenafil
  • rifampin
  • sildenafil
  • triazolam
  • venetoclax

The interactions that other medications may have with atazanavir and cobicistat vary from minor to severe, with the above medications all causing serious contradictions to your treatment. Hypersensitivity is particularly found in any antiepileptics including carbamazepine, phenobarbital and phenytoin and the antimycobacterial, rifampin. If you are taking any of these it is important to let your doctor know.

In some cases, it is necessary to co-administer atazanavir and cobicistat with other medicines due to the potential for serious or life-threatening adverse reactions. If you suffer from renal or hepatic impairment, it is likely you will be prescribed an anti-gout medication of colchicine. Sildenafil will be used for the treatment of pulmonary arterial hypertension whilst grazoprevir-containing products, including will be used to treat chronic hepatitis C infection. Other medicines used in combination with atazanavir and cobicistat may include variants of antihistamines, antiarrhythmics, antianginals, antipsychotics, neuroleptics, sedatives, platelet aggregation inhibitors and ergot derivatives.

In addition to this, dietary and lifestyle factors should be considered before starting your treatment. Alcohol can exacerbate certain side effects, as can smoking tobacco or eating certain sugars and salts. It is important to discuss the effects of food, alcohol and tobacco on atazanavir and cobicistat with your doctor, to ensure that you can experience the best treatment possible.


Before beginning your course of atazanavir and cobicistat, it is important that you discuss any prior allergies and sensitivities to a medication you may have taken in the past. Because this medicine can cause some serious side effects, it is important to be as transparent and honest with your doctor as possible.

Atazanavir and cobicistat is a medicine that requires lots of regular check-ups and tests with your doctor, no matter your level of health. Because of this, it is important to expect regular visits that are likely to include blood and urine tests.

There is a chance that your immune system will become stronger when you begin taking HIV medicines. For some, the immune system will start to combat infections that were previously concealed in the body, including pneumonia, herpes, and tuberculosis. In others, autoimmune disorders such as Graves' disease, polymyositis, and Guillain-Barré syndrome have been known to occur, although this is rarer. If you become aware of any changes to your health, contact your doctor.

Be diligent with any side effects you do experience, as there is the possibility for them to worsen or become severe. It is best to discuss any concerns or physical problems with your healthcare professional as soon as possible, to help control and manage adverse reactions. You must also be mindful of any new additions to your lifestyle or diet, as some vitamins and herbal supplements can be detrimental to your treatment.

Changes to your physical appearance may also become apparent, with the medicine having the possibility to cause extra body fat. This may be in the form of additional fat in the upper back, neck, chest or stomach. It may also be the loss of fat from the legs, arms or the face.

When taking this medication, be mindful that it does not reduce the risk of transmitting the HIV infection. This infection can be spread through sexual contact or contaminated blood. Be knowledgeable and only ever practice safe sex, using the right contraception to ensure that your partner will not be at risk. It is also vital that you do not share needles with anyone. In the scenario that you believe a partner may be at risk of infection, make sure that they see a doctor right away.

Atazanavir and cobicistat can have a detrimental effect on hormone-based birth control, making them more likely to be ineffective. If you are using implants, pills or vaginal rings you will need to discuss their effectivity and how you can make adjustments for more effective birth control, with your doctor.

The effects of taking atazanavir and cobicistat to an unborn child are unknown. A serious condition that causes a buildup of lactic acid in the blood (lactic acidosis) has been recorded as developing in some pregnant women. This has been known to happen whilst taking atazanavir and cobicistat alongside other HIV medicines called nucleoside reverse transcriptase inhibitors (NRTIs). Breastfeeding is never recommended for those who are taking this medication or those with HIV due to the possibility of spreading the infection. If you are pregnant or plan to become pregnant whilst taking this medicine, discuss any possible risks and effects it may have with your doctor.


As with all medication, it is important that you keep atazanavir and cobicistat in a safe area that children and vulnerable adults cannot access. This medicine should always be kept tightly closed in its original container at a temperature of 20°C to 25°C. The container will have a small packet of desiccant (a drying agent) with it, please do not remove this as it stops the medicine from being affected by moisture.

Always make sure that you dispose of atazanavir and cobicistat if it has expired, or if the original container seal is broken or missing. If you suspect that your tablets have been damaged or tampered with, dispose of them immediately and consult your doctor.


Atazanavir and cobicistat have the ability to prolong the progression of HIV, as well as some of the illnesses that it can cause. It is a long-term treatment that will act as part of a planned care plan, contributing to giving you a longer and healthier life.

Because of its oral administration, it can be managed effectively and with ease. However, this can also be a problem, with some people finding it difficult to take consistent doses at regular times. There are many methods to cope with this issue, from taking medicines at set mealtimes and using daily dosing containers to setting alarms on a phone or clock. For guidance on methods to regularly take your medicine, it is important to discuss it with your healthcare provider.

Atazanavir and cobicistat have the potential to cause some unpleasant side effects, with the most common ones being stomach related. Abdominal distension, dysgeusia and dyspepsia can all impact a person's daily routine, but can all be successfully managed with help from your doctor. Be prepared to have regular visits and checkups as well as making changes to your lifestyle and diet. This will all contribute to your treatment being its best and causing the least impact on your life.

For those who have pre-existing conditions or diseases, it is vital that you discuss them with your doctor and have total transparency. Atazanavir and cobicistat can have some serious reactions to other medications or illnesses, and its treatment will need to be tracked carefully for anyone in this position. For those with diabetes, haemophilia, hepatitis B, hepatitis C and any heart, liver or kidney problems, it is particularly important that your doctor provides extra tests and appointments, as they can all have serious implications.

It is also important to discuss any birth control that you may be taking, as this medication can have a negative effect and cause hormone-based birth control to be less effective.

With the effective use of atazanavir and cobicistat alongside other antiretroviral medications, a patient's HIV can be maintained and its progression slowed down, enabling them to make positive changes to their lives and the people in it.

To achieve the best results from this medication, it requires plenty of commitment and responsibility. You must be diligent with your treatment routine and mindful of any dietary or lifestyle factors that may affect your treatment. A strong link to communication between your doctor and you is hugely important, as side effects will need to be closely monitored.

Last Reviewed:
December 25, 2017
Last Updated:
April 05, 2018