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What is Sustiva (Efavirenz) Used For? Side Effects and Dosage

What is Sustiva (Efavirenz) Used For? Side Effects and Dosage

What is Sustiva (Efavirenz)?

Sustiva, also referred to as Efavirenz, is a medication used in the treatment of human immunodeficiency virus (HIV), the virus responsible for the development of acquired immunodeficiency syndrome (AIDS) in the human body. This drug is a non-nucleoside reverse transcriptase inhibitor (NNRTI), a class of medications designed to prevent the creation of viral DNA in a patient via an enzyme called reverse transcriptase. As with other antiretroviral medications, Sustiva is not a cure for HIV and is instead intended to be used in conjunction with other similar medications to stop the spread of the virus in the body. The drug was introduced in 1998 and is marketed in North America by Bristol-Myers Squibb. It is currently listed as one of the World Health Organization’s essential medicines, owing to its utility and success in treating HIV.

What is It Used For?

As discussed above, Sustiva medication is used in the treatment of individuals with HIV, specifically HIV Type 1 (HIV-1). HIV-1 is more common than its less infectious counterpart, HIV-2; it accounts for approximately 95 per cent of worldwide HIV infections. Efavirenz is used to treat patients who are treatment naïve, meaning they have not yet received any medications or treatments for their infection. As an NNRTI, the medication’s mechanism of action is its ability to bind to the reverse transcriptase molecule, which inhibits the polymerization (replication of molecular chains) of DNA from viral ribonucleic acid by changing the locations of amino acids in the bound chain.

How to take Efavirenz

Sustiva is available in capsule and tablet form; the capsules are available in 50 mg, 100 mg, or 200 mg sizes, while the film-coated tablets are 600 mg in size. Both are intended to be taken orally by being swallowed whole. Tablets should not be crushed, while capsules may be sprinkled over a very small amount of food if swallowing whole is infeasible.

In order to reduce the risk of severe side effects, Sustiva should be taken on an empty stomach whenever possible, as food may unsafely increase the blood level of the medication. It is advised that Efavirenz is instead taken immediately prior to sleeping.  As with many medications, grapefruit and grapefruit juice should be avoided while taking Sustiva, as this can negatively affect the medication’s bodily absorption.

Sustiva Side Effects

Various side effects have been observed in patients taking Sustiva. To reduce the risk of side effects, prospective patients should consult with their health care provider regarding any other medications being taken, as these may interact with Sustiva and increase the likelihood and severity of side effects.

The following side effects have been observed more frequently:

  • nausea and vomiting
  • abnormal dreaming
  • insomnia
  • changes in body fat shape and location
  • drowsiness
  • dizziness

The following side effects occur less frequently, but may require immediate medical attention:

  • rash
  • skin peeling
  • loss of balance
  • psychiatric symptoms such as depression, anxiety, or thoughts of self-harm
  • profuse sweating
  • fever
  • discoloring of urine or stool
  • wheezing, coughing, or shortness of breath
  • stomach pain
  • yellowing of skin, nails, or eyes

In addition to the above, Sustiva has been observed to increase the risk of fetal neural tube defects in first-trimester pregnant women. As such, the medication should be avoided by this group of patients.


Sustiva is intended to be taken by individuals weighing at least 3.5 kg (7.7 lbs) and at least 3 months of age. In patients whose weights range between 3.5 kg and 40 kg (88 lbs), the dosage is to be determined by their health care provider, beginning at 100 mg per day for lower weights and increasing incrementally to 400 mg per day for higher weights. This is taken in the form of capsules, in either 50 mg, 100 mg, or 200 mg forms. For patients with weights 40 kg or above, the dosage is 600 mg per day, taken as either one 600 mg tablet or three 200 mg capsules. If a dose is missed, patients are advised to take their medication as soon as possible. If a dose has been skipped altogether, the next dose should not be doubled, and patients should instead resume their regular schedule at the following dose.

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