Common use

Efavirenz is a non-nucleoside reverse transcriptase inhibitor (NNRTI) — a class of antiretroviral medications specifically designed to combat Human Immunodeficiency Virus (HIV) infection. It is prescribed as a key component of highly active antiretroviral therapy (HAART) for the treatment of HIV-1 infection in adults and children, and may also be used in certain post-exposure prophylaxis (PEP) regimens to help prevent HIV infection in individuals who have experienced occupational or non-occupational exposure to the virus, such as through needlestick injuries, sexual contact with HIV-positive individuals, or other high-risk exposures.

Efavirenz works by selectively binding to and inhibiting the HIV-1 reverse transcriptase enzyme, which the virus requires to convert its RNA genetic material into DNA — a critical step in viral replication. By blocking this enzyme, Efavirenz prevents the virus from creating copies of itself, thereby reducing the viral load in the patient's blood and allowing the immune system to recover and strengthen. Efavirenz is always used in combination with other antiretroviral drugs (never as monotherapy) to maximize effectiveness and reduce the risk of viral resistance. It is a preferred first-line treatment component recommended by the World Health Organization (WHO) and major HIV treatment guidelines. When you buy Efavirenz online, you access an essential antiretroviral medication that has helped millions of people living with HIV achieve viral suppression and improved quality of life.



Dosage and direction

The standard recommended dose of Efavirenz for adults and adolescents weighing more than 40 kg is 600 mg taken once daily, preferably on an empty stomach at bedtime. Taking Efavirenz before sleep is strongly recommended, particularly during the first two to four weeks of therapy, as this timing helps minimize the neuropsychiatric side effects (dizziness, vivid dreams, difficulty concentrating) that are most pronounced when the drug is first initiated. Pediatric dosing is weight-based: children weighing 13-15 kg receive 200 mg daily, 15-20 kg receive 250 mg daily, 20-25 kg receive 300 mg daily, 25-32.5 kg receive 350 mg daily, and 32.5-40 kg receive 400 mg daily. Swallow the capsules or tablets whole with water — do not crush, break, or chew them. Efavirenz must be taken consistently every day at approximately the same time to maintain stable blood levels and ensure optimal viral suppression. Missing doses or taking the medication irregularly can lead to treatment failure and the development of drug-resistant HIV strains.



Precautions

Before starting Efavirenz therapy, inform your healthcare provider about your complete medical history, including any liver or kidney disease, alcohol dependence or substance abuse, history of hepatic encephalopathy, elevated cholesterol or triglycerides, hepatitis B or C co-infection, history of mental health conditions (depression, anxiety, suicidal ideation), seizure disorders, or previous use of other NNRTIs such as delavirdine (Rescriptor) or nevirapine (Viramune) without achieving viral suppression. Special caution is required for children under 3 years of age and children weighing less than 13 kg, as the safety and efficacy of Efavirenz in these populations have not been well established.

Women of childbearing potential must use highly effective contraception (preferably a barrier method in addition to hormonal contraception, since Efavirenz can reduce the effectiveness of hormonal birth control) throughout Efavirenz treatment and for 12 weeks after discontinuation, as this medication is classified as a known teratogen and can cause serious birth defects, particularly neural tube defects, if taken during the first trimester of pregnancy. Pregnancy testing should be performed before initiating therapy. Patients should be aware that Efavirenz does not cure HIV infection and does not prevent HIV transmission — safer sex practices and precautions must be maintained.



Contraindications

Efavirenz is contraindicated in patients with known hypersensitivity to the drug or any of its components. It must not be used during pregnancy or by women who may become pregnant during treatment due to the significant risk of teratogenic effects. Breastfeeding while taking Efavirenz is not recommended, as HIV can be transmitted through breast milk and the drug is excreted in breast milk. Efavirenz should not be co-administered with certain medications that are primarily metabolized by CYP3A4 or CYP2B6 and have a narrow therapeutic index, as dangerous drug interactions may occur.



Side effects

Efavirenz is associated with distinctive neuropsychiatric side effects, which are most common during the first few weeks of therapy and typically diminish over time. These may include vivid or disturbing dreams, dizziness, impaired concentration, insomnia, drowsiness, and a general feeling of mental "fogginess." However, some patients may experience more serious psychiatric symptoms that require immediate medical attention, including hallucinations, suicidal thoughts or ideation, severe depression, aggressive behavior, paranoia, extreme anxiety, confusion, or unusual behavioral changes. If you or someone around you notices any of these symptoms, contact your healthcare provider immediately.

Other common side effects include skin rash (which can rarely progress to severe Stevens-Johnson syndrome), elevated liver enzymes, increased cholesterol and triglyceride levels, nausea, headache, and fatigue. Lipodystrophy (changes in body fat distribution) may develop with long-term antiretroviral therapy. Immune reconstitution inflammatory syndrome (IRIS) may occur as the immune system recovers, potentially unmasking previously dormant infections. Report any unusual symptoms to your HIV specialist promptly.



Drug interaction

Efavirenz has numerous and clinically significant drug interactions due to its effects on hepatic cytochrome P450 enzymes. It decreases blood concentrations and therapeutic effects of several HIV protease inhibitors, including indinavir (Crixivan) and saquinavir (Invirase), requiring dosage adjustments when used in combination. Alcohol consumption should be avoided or minimized, as it can amplify Efavirenz's central nervous system effects including dizziness and impaired judgment. Co-administration with astemizole or cisapride increases the risk of serious cardiac arrhythmias. Efavirenz significantly reduces the effectiveness of hormonal contraceptives (birth control pills, patches, rings), necessitating the use of additional barrier contraception methods.

When used with ritonavir, both the side effects of Efavirenz and the risk of hepatotoxicity (liver damage) are increased. Concomitant use with clarithromycin, saquinavir, or certain antifungal medications should be avoided or carefully managed. Midazolam and triazolam can have dangerously enhanced sedative effects when combined with Efavirenz. Phenobarbital, phenytoin, and carbamazepine may decrease Efavirenz blood levels, potentially compromising viral suppression. Rifampin and rifabutin interactions require careful dose adjustments.

Do not take Efavirenz with pimozide (Orap), cisapride (Propulsid), or ergot alkaloid medications such as ergotamine (Cafergot, Wigraine, Ergomar), dihydroergotamine, ergonovine (Ergotrate), or methylergonovine (Methergine), as these combinations can cause life-threatening adverse reactions. St. John's Wort should also be avoided as it can significantly reduce Efavirenz levels.



Missed dose

If you miss a dose of Efavirenz, take it as soon as you remember, provided it is not too close to the time for your next scheduled dose. If your next dose is coming up soon, skip the missed dose and take your next dose at the regular time. Never take a double dose to compensate for a missed one. Consistent daily dosing is crucial for maintaining viral suppression and preventing the development of drug-resistant HIV. If you frequently miss doses, discuss strategies with your healthcare provider to improve adherence, such as setting daily reminders or using pill organizers.



Overdose

Symptoms of Efavirenz overdose may include intensified neuropsychiatric symptoms such as involuntary muscle twitching, tremors, severe dizziness, agitation, and confusion. In the event of a suspected overdose, seek emergency medical attention immediately. Treatment is generally supportive, and there is no specific antidote for Efavirenz. Activated charcoal may be used to help reduce further absorption if administered soon after ingestion.



Storage

Store Efavirenz at room temperature between 68-77 degrees F (20-25 degrees C), protected from moisture, direct sunlight, and excessive heat. Keep the medication in its original container with the lid tightly closed. Do not store in the bathroom or other humid environments. Keep all antiretroviral medications securely out of the reach of children and pets. Do not use after the expiration date.



Disclaimer

We provide only general information about medications which does not cover all directions, possible drug integrations, or precautions. Information at the site cannot be used for self-treatment and self-diagnosis. Any specific instructions for a particular patient should be agreed with your health care adviser or doctor in charge of the case. We disclaim reliability of this information and mistakes it could contain. We are not responsible for any direct, indirect, special or other indirect damage as a result of any use of the information on this site and also for consequences of self-treatment.