Sustiva (Efavirenz) — Patient Information (Australia)

Sustiva is a prescription medicine containing efavirenz, used as part of combination antiretroviral therapy for HIV. This guide explains how efavirenz works, how it is usually taken, important interactions, and practical tips to help you use it safely and effectively. It is written for people in Australia and does not replace medical advice from your healthcare team.

Indications: What Sustiva is used for

Sustiva (efavirenz) is used for the treatment of HIV infection. It is generally used in combination with other antiretroviral medicines to help suppress HIV to undetectable levels and reduce the risk of illness progression.

Your clinician may recommend efavirenz as part of a first-line or later treatment plan depending on your prior therapy, drug resistance, other medicines you take, and individual factors such as age, liver function, and pregnancy status.

How Sustiva works (Mechanism of action)

Efavirenz belongs to the class of medicines called NNRTIs (non-nucleoside reverse transcriptase inhibitors). HIV uses an enzyme called reverse transcriptase to copy its genetic material inside human cells.

• Efavirenz binds to reverse transcriptase and alters how it functions.
• This blocks the conversion of viral RNA into DNA, which is needed for HIV to reproduce.
• With combination therapy, this helps reduce viral load and allows immune function to recover over time.

Pharmacokinetics: How efavirenz moves through the body

Pharmacokinetics describes how the body absorbs, distributes, metabolises, and eliminates a medicine. Understanding these points can help explain dosing timing and why interactions matter.

• Absorption: Efavirenz is absorbed after oral dosing. Blood levels can be influenced by food intake (see “Food interactions”).
• Distribution: It distributes widely in the body, including into tissues where HIV may replicate.
• Metabolism: Efavirenz is primarily metabolised in the liver, largely via the enzyme system CYP (notably CYP2B6 and CYP3A4). This is why other medicines that affect liver enzymes may change efavirenz levels.
• Elimination: Metabolites are cleared mainly through the body’s normal routes (including bile and urine).
• Long activity: Efavirenz has a relatively long persistence in the body, which is one reason once-daily dosing is possible.

Typical dosing and timing

Doses vary by age, body weight, and the specific formulation available. Your healthcare professional will decide the exact dose for you. Below is general information to help you understand typical use.

Common adult approach

• Many adults take efavirenz once daily.
• It is often taken at bedtime to reduce the chance of certain nervous system side effects (such as dizziness or vivid dreams).

Children and adolescents

Paediatric dosing is usually weight-based and must follow local clinical guidance and the product information. Dosing in children can be different from adults.

Missed doses

If you miss a dose, follow your clinician’s instructions or the directions on your medicine label. In general:

• Take the missed dose as soon as you remember if it is not close to the next dose.
• If it is nearly time for the next dose, skip the missed dose and continue your regular schedule.
• Do not double up unless your clinician advises it.

How to take Sustiva (Practical use tips)

Efavirenz works best when taken consistently and as part of a combination HIV regimen. Consider these practical tips:

• Take it at the same time each day to maintain steady levels.
• Bedtime dosing: If you experience dizziness or sleep disturbances, taking it at night may help.
• Do not stop or change HIV medicines without guidance—stopping can lead to viral rebound and treatment failure.
• Use a pill organiser or phone reminders to improve adherence.
• Report side effects early—many improve with time or adjustment.
• Attend regular blood tests (viral load, immune markers, and safety monitoring).

Food interactions: What to know

Food can influence efavirenz absorption. Many people find dosing is easiest with their usual routine, but it’s important to follow specific advice from your pharmacist or prescriber.

• Try to take efavirenz consistently in relation to meals (for example, always with a light snack or always on an empty stomach), unless your clinician instructs otherwise.
• Higher-fat meals may increase efavirenz blood levels, which can make side effects more noticeable in some people.
• If you notice worsening dizziness, sleep changes, or nausea after meals, speak to your healthcare team—timing or regimen changes may help.

Alcohol and medicine interactions

Efavirenz may cause nervous system side effects in some people, such as dizziness, drowsiness, abnormal dreams, or difficulty concentrating. Alcohol can worsen these effects, making it more difficult to drive or operate machinery safely.

Alcohol

• Avoid heavy alcohol intake—it can intensify dizziness and impair judgement.
• If you drink alcohol, do so cautiously and monitor how you feel.
• Do not drive or use machinery if alcohol and/or efavirenz make you feel unwell.

Common medicine interaction themes

Efavirenz is metabolised by liver enzymes. Medicines that affect those enzymes can change efavirenz levels or the levels of other drugs. This can affect both safety and effectiveness.

• Anticonvulsants (anti-seizure medicines): some can lower efavirenz levels and reduce effectiveness.
• Antimycobacterials: certain TB medications can alter efavirenz levels.
• Antifungal medicines: some can increase efavirenz levels, increasing side effects risk.
• Antibiotics: some can affect metabolism; others may require dose adjustment or monitoring.
• Hormonal contraception: efavirenz can affect sex hormone levels in some situations, which may reduce contraceptive effectiveness. Use appropriate contraception guidance.
• St John’s wort: can significantly reduce efavirenz levels and is generally not recommended with many HIV therapies.

Always provide your pharmacist or clinician with a full list of prescription medicines, over-the-counter medicines, vitamins, and herbal products. If you start or stop any medicine, ask whether it interacts with efavirenz.

Safety profile: What to expect and when to seek help

Most people tolerate efavirenz when used correctly, especially as part of modern combination regimens. However, efavirenz has a specific safety profile. Some side effects are more common early in treatment and may lessen over time.

Common side effects

• Dizziness or feeling light-headed
• Drowsiness or fatigue
• Sleep disturbances and vivid dreams
• Nausea
• Headache
• Skin rash (may occur; severity varies)
• Elevated liver enzymes on blood tests (requires monitoring)

Serious side effects: Get urgent medical advice

Seek urgent help if you experience:

• Severe allergic reaction (swelling of face/lips, trouble breathing, widespread hives)
• Severe rash, blistering, skin peeling, or rash with fever or mouth sores
• Severe mood or mental health symptoms (for example, confusion, hallucinations, extreme agitation, or suicidal thoughts)
• Signs of liver problems (yellowing of the eyes/skin, dark urine, severe upper abdominal pain, persistent vomiting)
• Convulsions or fainting

Pregnancy and breastfeeding considerations

Efavirenz is known to have considerations in pregnancy. If you are pregnant, planning pregnancy, or breastfeeding, discuss risks and benefits with your clinician promptly. Effective contraception guidance is important for people who can become pregnant.

Kidney function

Efavirenz is primarily cleared through liver metabolism. Your clinician will still monitor overall health, but kidney impairment usually does not drive dosing in the same way as with some other antiretrovirals.

Recent guidance and monitoring (Australia-focused)

In Australia, HIV management is guided by national clinical recommendations and specialist care. Monitoring typically includes:

• Viral load testing to ensure treatment is suppressing HIV
• CD4/immune marker testing as needed
• Liver function tests and safety monitoring (especially in people with liver disease or when taking interacting medicines)
• Assessment for side effects, including nervous system and skin symptoms

Because guidance can update over time, your clinic may recommend regimen changes based on resistance patterns, tolerability, and current best practice. Always follow the advice of your HIV specialist or treating doctor.

Alternative options

Treatment for HIV is individualised. Depending on your history, resistance tests, and tolerability, clinicians may use other antiretroviral options instead of efavirenz. Alternatives may include medicines from the NNRTI class (other than efavirenz) or medicines from different classes such as:

• Integrase inhibitors
• Protease inhibitors (sometimes with boosters)
• Nucleos(t)ide reverse transcriptase inhibitors in combination regimens

Your clinician will consider drug–drug interactions, pregnancy plans, mental health history, liver function, and convenience (including dosing schedule) when choosing an alternative.

Delivery and availability in Australia

Access to Sustiva (efavirenz) depends on local availability, pharmacy supply, and your healthcare pathway. In Australia, antiretroviral medicines are generally supplied via authorised channels.

• Availability: Stock may vary between suppliers and regions.
• Packaging: Medicines are dispensed in manufacturer packaging or pharmacist-labelled containers.
• Delivery: Delivery options depend on the online pharmacy’s service area, cold-chain requirements (usually not required for tablets), and courier scheduling.
• Identification and compliance: Reliable online dispensing follows Australian regulatory requirements and pharmacy standards.

If you’re purchasing online, ensure your order details match your medicine label requirements and that you receive medication from a reputable Australian pharmacy. If you have questions about ordering timeframes, speak with the pharmacy customer service team.

Market and legal context for Australia (overview)

HIV medicines like efavirenz are regulated therapeutic goods in Australia. Supply is typically managed through prescription processes and dispensing by authorised pharmacists, often under Commonwealth arrangements depending on eligibility.

Australian patients and pharmacies generally follow standards for:

• Quality and traceability of medicines
• Appropriate patient counselling and documentation
• Safety screening for interactions and contraindications
• Adherence support and monitoring plans

Eligibility for subsidies (such as the PBS) depends on individual circumstances and should be confirmed by your pharmacist or clinic.

Safety FAQ (Frequently Asked Questions)

1) Why do I need to take Sustiva at bedtime?

Efavirenz can cause nervous system side effects such as dizziness, drowsiness, and vivid dreams, especially at the start of therapy. Taking it at bedtime may reduce the impact while you sleep and help you cope with daytime effects.

2) Can I take Sustiva with food?

You should follow the specific directions given for your regimen. Food can change efavirenz absorption, and higher-fat meals may increase levels. Many people are advised to take it in a consistent way with regard to meals.

3) What happens if I miss a dose?

Take the missed dose when you remember if it is not near your next dose, then continue your regular schedule. If it’s almost time for the next dose, skip the missed one. Do not double up unless your healthcare professional advises it.

4) What medicines commonly interact with efavirenz?

Medicines that affect liver enzymes can change efavirenz levels. This includes some anticonvulsants, TB medicines, certain antifungals, some antibiotics, hormonal contraceptives, and herbal products such as St John’s wort. Always check with your pharmacist before starting or stopping anything.

5) Can I drink alcohol while taking Sustiva?

Moderate to heavy alcohol may worsen dizziness, drowsiness, and judgement. It’s best to avoid heavy drinking and not drive if you feel affected. If you’re unsure, discuss safe limits with your clinician.

6) How will I know if it’s working?

Your HIV clinic will use blood tests, especially viral load and sometimes CD4 counts, to confirm that treatment is suppressing HIV. If the viral load doesn’t decrease as expected, resistance testing and regimen review may be needed.

7) Does efavirenz cause rash?

Rash can occur, particularly in early treatment. Mild rash may be manageable, but severe rash with blistering, skin peeling, fever, or mouth sores needs urgent medical attention.

8) Is it safe to drive or operate machinery?

Efavirenz may cause dizziness or sleepiness. Until you know how the medicine affects you—especially in the first few weeks—avoid driving if you feel unwell. Alcohol can increase the risk of impaired driving.

9) What monitoring do I need while on efavirenz?

Typical monitoring includes viral load and immune markers, plus periodic blood tests such as liver function tests. Your clinician may also monitor mental health symptoms and assess skin reactions.

10) What should I do if I feel depressed, confused, or have unusual thoughts?

If you experience significant mood changes, confusion, hallucinations, or thoughts of self-harm, seek urgent medical assistance. Do not stop your HIV medicines without medical advice, but get help immediately for safety.

Summary: Key points to remember

• Sustiva (efavirenz) is an NNRTI used in combination to treat HIV.
• It is usually taken once daily, often at bedtime.
• Food—especially higher-fat meals—can affect drug levels, so keep dosing consistent with your clinician’s instructions.
• Alcohol may worsen dizziness or sleepiness; use caution and avoid driving if affected.
• Drug interactions can be significant—always review all medicines and herbal products with a pharmacist.
• Regular monitoring and early reporting of side effects improve safety and treatment success.

This information is intended as a general guide for patients. Your healthcare team can provide advice tailored to your health history, current medicines, and laboratory results.