What is Efavirenz: Uses, Dosage, Side Effects and More

Efavirenz is a prescription medication that helps treat HIV infection by blocking the virus from multiplying in your body. It belongs to a class of drugs called non-nucleoside reverse transcriptase inhibitors (NNRTIs), which work like a key that stops HIV from making copies of itself. This medicine is typically taken once daily as part of a combination therapy with other HIV medications to help keep the virus under control and protect your immune system.

What is Efavirenz?

Efavirenz is an antiviral medication specifically designed to fight HIV-1, the most common type of HIV. It works by interfering with an enzyme called reverse transcriptase that HIV needs to reproduce inside your cells. Think of it as putting a lock on the door that prevents the virus from entering and taking over your healthy cells.

This medication has been helping people with HIV live healthier lives for over two decades. It's considered a moderate-strength HIV medicine that works well when combined with other antiretroviral drugs. You'll always take efavirenz as part of a combination treatment plan, never alone, because using multiple medications together is much more effective at controlling HIV.

What is Efavirenz Used For?

Efavirenz is primarily used to treat HIV-1 infection in adults and children who weigh at least 40 kilograms (about 88 pounds). It's part of what doctors call highly active antiretroviral therapy (HAART), which combines different types of HIV medications to create a powerful treatment approach.

Your doctor might prescribe efavirenz if you're starting HIV treatment for the first time or if you need to switch from another medication due to side effects or resistance. It's particularly useful for people who want the convenience of once-daily dosing. The goal is to reduce your viral load to undetectable levels, which means the virus becomes so suppressed that it can't be transmitted to others.

Sometimes doctors also prescribe efavirenz as part of post-exposure prophylaxis (PEP) in emergency situations where someone has been exposed to HIV. However, this use is less common and requires careful medical supervision.

How Does Efavirenz Work?

Efavirenz works by targeting a specific step in HIV's reproduction process. When HIV infects your cells, it needs to convert its genetic material from RNA to DNA using an enzyme called reverse transcriptase. Efavirenz binds directly to this enzyme and blocks it from working properly.

This blocking action prevents HIV from integrating into your cell's DNA, which stops the virus from making new copies of itself. It's like jamming the virus's copying machine so it can't reproduce. While efavirenz doesn't cure HIV, it dramatically reduces the amount of virus in your blood when used consistently.

The medication is considered moderately potent compared to some newer HIV drugs, but it remains highly effective when taken as prescribed. It typically takes several weeks to see the full effect on your viral load, and you'll need regular blood tests to monitor how well it's working.

How Should I Take Efavirenz?

Take efavirenz exactly as your doctor prescribes, usually once daily on an empty stomach. The best time is typically at bedtime, about 1-2 hours after your last meal, because this timing can help reduce some side effects like dizziness or vivid dreams.

Swallow the tablet or capsule whole with water. Don't crush, chew, or open the medication as this can affect how your body absorbs it. If you're taking the liquid form, measure it carefully with the provided measuring device, not a household spoon.

Taking efavirenz on an empty stomach is important because food can increase the amount of medication your body absorbs, potentially leading to more side effects. However, if you experience severe stomach upset, talk to your doctor about the best approach for your situation.

Try to take your dose at the same time each day to maintain steady levels in your blood. Setting a daily alarm or using a pill organizer can help you remember. If you travel across time zones, ask your doctor how to adjust your dosing schedule.

How Long Should I Take Efavirenz For?

You'll typically need to take efavirenz for as long as it remains effective in controlling your HIV, which could be many years or even indefinitely. HIV treatment is generally a lifelong commitment, and stopping your medication can allow the virus to multiply rapidly and potentially develop resistance.

Your doctor will monitor your response through regular blood tests that measure your viral load and CD4 cell count. If efavirenz continues to keep your viral load suppressed and you tolerate it well, you may stay on this medication for years. Some people have taken efavirenz successfully for over a decade.

However, you might need to switch medications if you develop side effects that don't improve, if the virus develops resistance, or if newer, more convenient options become available. Never stop taking efavirenz suddenly without consulting your doctor, as this can lead to viral rebound and potential resistance.

If you're planning to become pregnant or are experiencing persistent side effects, discuss timing for potential medication changes with your healthcare team. They can help you transition safely to alternative treatments if needed.

What Are the Side Effects of Efavirenz?

Like all medications, efavirenz can cause side effects, though not everyone experiences them. The good news is that many side effects are temporary and improve as your body adjusts to the medication, usually within the first few weeks of treatment.

The most common side effects you might experience include:

• Vivid dreams or nightmares
• Dizziness or feeling "foggy"
• Trouble sleeping or changes in sleep patterns
• Nausea or upset stomach
• Headaches
• Fatigue or feeling unusually tired
• Rash (usually mild and temporary)

These effects are often most noticeable during your first month of treatment and typically become less bothersome over time. Taking your dose at bedtime can help minimize the impact of dizziness and sleep-related side effects.

Some people experience more serious but less common side effects that require immediate medical attention:

• Severe skin reactions or widespread rash
• Signs of liver problems (yellowing of skin or eyes, dark urine, severe stomach pain)
• Severe depression or thoughts of self-harm
• Persistent confusion or memory problems
• Severe mood changes or aggression

Contact your doctor right away if you experience any of these more serious symptoms. In rare cases, efavirenz can affect your mental health or cause seizures, especially in people with a history of psychiatric conditions.

Who Should Not Take Efavirenz?

Efavirenz isn't suitable for everyone, and your doctor will carefully review your medical history before prescribing it. You should not take efavirenz if you're allergic to it or have had a severe reaction to it in the past.

People with certain medical conditions need special consideration or may need to avoid efavirenz altogether:

• Severe liver disease or hepatitis B or C
• History of mental health conditions like severe depression or psychosis
• Seizure disorders or epilepsy
• Known QT prolongation (heart rhythm condition)
• Pregnancy (especially first trimester)

If you have a history of substance abuse, your doctor will weigh the risks and benefits carefully, as efavirenz can sometimes worsen psychiatric symptoms. People with kidney problems can usually take efavirenz, but may need dose adjustments.

Tell your doctor about all medications you're taking, including over-the-counter drugs and herbal supplements. Efavirenz can interact with many other medications, including some antidepressants, seizure medications, and even St. John's wort.

Efavirenz Brand Names

Efavirenz is available under several brand names, with Sustiva being the most well-known single-ingredient formulation. This brand was one of the first efavirenz products available and helped establish the medication's reputation in HIV treatment.

You might also receive efavirenz as part of combination pills that include other HIV medications. Popular combination brands include Atripla (efavirenz + tenofovir + emtricitabine) and Symfi (efavirenz + tenofovir + lamivudine). These combination pills can make treatment more convenient by reducing the number of pills you need to take daily.

Generic versions of efavirenz are now available and work just as effectively as brand-name versions. Your insurance may prefer generic options, which can significantly reduce your medication costs. Always check with your pharmacist if you have questions about which version you're receiving.

Efavirenz Alternatives

If efavirenz doesn't work well for you, several alternative HIV medications can provide similar benefits. Your doctor might consider switching you to other NNRTIs like rilpivirine (Edurant) or doravirine (Pifeltro), which tend to have fewer psychiatric side effects.

Integrase inhibitors represent another class of HIV medications that many doctors now prefer as first-line treatment. These include dolutegravir (Tivicay), bictegravir (found in Biktarvy), and raltegravir (Isentress). These medications often have fewer side effects and are less likely to cause sleep disturbances or mood changes.

For people who need once-daily dosing, combination pills like Biktarvy, Triumeq, or Dovato might be excellent alternatives. These newer combinations are often more tolerable and equally effective at suppressing HIV.

The choice of alternative depends on factors like your other medications, kidney function, potential drug interactions, and personal preferences. Your doctor will work with you to find the best option if efavirenz isn't the right fit.

Is Efavirenz Better Than Dolutegravir?

Both efavirenz and dolutegravir are effective HIV medications, but they work differently and have distinct advantages. Dolutegravir, an integrase inhibitor, has generally become the preferred choice for many doctors because it tends to cause fewer side effects and has a higher barrier to resistance.

Efavirenz has been around longer and has an extensive track record of success, with decades of real-world use showing its effectiveness. It remains an excellent option for many people, especially those who tolerate it well and prefer the convenience of once-daily dosing.

Dolutegravir typically causes fewer psychiatric side effects like vivid dreams or mood changes that some people experience with efavirenz. However, dolutegravir might cause weight gain in some people, which is less common with efavirenz.

The "better" choice depends on your individual circumstances, including your medical history, other medications, and how you respond to treatment. Both medications are considered highly effective when taken as prescribed, and either can help you achieve an undetectable viral load.