Sustiva (Efavirenz) – Patient-Friendly Medicine Information (Australia)

Sustiva is a brand of the antiretroviral medicine efavirenz. It is used as part of combination therapy for HIV infection. This page explains how Sustiva works, how it is typically taken, what to expect, and important safety and interaction considerations for people in Australia.

Medicines information should always be read alongside the product’s Consumer Medicine Information (CMI) and advice from a qualified healthcare professional. If you are unsure about any aspect of your treatment, speak with your HIV specialist or pharmacist.

Quick facts

• Medicine: Sustiva (efavirenz)
• What it is used for: HIV infection, as part of combination therapy
• How it works: Blocks HIV replication by inhibiting HIV reverse transcriptase
• Common dosing approach: Usually taken once daily, often at bedtime
• Key safety themes: Central nervous system effects, rash, liver monitoring, pregnancy considerations
• Important interactions: Many drug interactions (including some medicines that affect the liver enzymes)

Basic product information

Mechanism of action (how Sustiva works)

HIV replicates by converting its genetic material into DNA using an enzyme called reverse transcriptase. Sustiva (efavirenz) belongs to a class called NNRTIs. It binds to HIV reverse transcriptase and blocks the enzyme’s function, preventing HIV from making copies of itself.

On its own, efavirenz is not sufficient to treat HIV. Sustiva is used with other antiretroviral medicines to:

• Reduce viral load rapidly
• Prevent resistance from developing
• Improve long-term control of HIV

Pharmacokinetics (how the body handles efavirenz)

Understanding pharmacokinetics can help explain timing, side effects, and interactions.

• Absorption: Efavirenz is absorbed after oral dosing; taking it regularly helps maintain steady levels.
• Distribution: It spreads throughout the body and reaches target sites relevant to viral replication.
• Metabolism: Efavirenz is primarily processed by the liver enzymes (notably the CYP450 system). This is why drug–drug interactions can be important.
• Half-life: Efavirenz has a long elimination half-life, meaning missing doses may affect overall drug levels more than you might expect.
• Food effects: Food—especially high-fat meals—can increase efavirenz levels, which may increase the likelihood of side effects in some people.

Typical use

Sustiva is used for the treatment of HIV infection in adults and, in some settings, children—always as part of an individualised combination antiretroviral regimen.

Your regimen will be chosen based on factors such as prior treatment history, viral resistance testing (where applicable), kidney and liver health, pregnancy potential, and interaction risk with other medicines.

Indications (what it’s used to treat)

Efavirenz is indicated for the treatment of HIV infection in combination with other antiretroviral agents. It is not used for prevention after exposure unless specifically directed under local clinical protocols.

How to take Sustiva: timing, dosing and practical steps

Below are general patient-friendly guidance points. Your dosing schedule must follow the instructions provided by your prescribing clinician and the CMI.

Typical dosing approach

Many patients take efavirenz once daily. In many regimens, it is commonly taken at bedtime to help reduce daytime central nervous system side effects (for example, dizziness or vivid dreams).

Common dosing principles

• Take at the same time each day to help maintain consistent drug levels.
• Follow your clinician’s schedule for your specific tablet strength and combination medicines.
• Do not stop or change antiretroviral therapy without medical advice. Stopping can lead to viral rebound and resistance.

Missed dose guidance (general)

If you miss a dose, take it as soon as you remember unless it is close to the time of your next dose. If it is near your next dose, skip the missed dose and resume your usual schedule. Avoid doubling up.

If you are unsure, ask your pharmacist for advice based on your dosing time and the regimen you are using.

Practical use tips

• Bedtime dosing: Taking it at night may reduce the impact of early dizziness or sleep-related symptoms.
• Hydration and routine: Consider taking it with a glass of water and keeping a consistent daily routine.
• Track side effects: If you notice new symptoms after starting or changing dose, note when they occur and discuss them promptly.
• Adherence tools: Pill boxes, smartphone reminders, or blister packs can help prevent missed doses.

Food interactions (what to eat and drink)

Food can affect how much efavirenz your body absorbs. In general:

• High-fat meals may increase efavirenz exposure and the risk of side effects.
• Many people are advised to take efavirenz on an empty stomach or with light food. Follow the instructions provided in the CMI or by your clinician.

If you experience increased dizziness, nausea, or sleep disturbance after meals, discuss it with your pharmacist—your regimen may be adjusted, or advice on meal timing may help.

Alcohol and medicine interactions

Alcohol

Alcohol may worsen dizziness, drowsiness, and impaired concentration. Efavirenz can also affect the nervous system, especially during the early days of therapy. For safety:

• Avoid heavy alcohol use, particularly when you first start or restart efavirenz.
• If you drink alcohol, do so cautiously and consider how you feel after taking your dose.
• Do not drive or operate machinery if you feel sleepy, dizzy, or “out of it.”

Medicine interactions

Efavirenz is metabolised by liver enzymes and can also influence them. As a result, it can interact with many medicines, including prescription, over-the-counter products, and supplements.

Always tell your pharmacist and clinician about:

• All HIV medicines you take
• Medicines for tuberculosis (TB), hepatitis, or fungal infections
• Anticonvulsants
• Antidepressants and other mental health medicines
• Hormonal contraceptives
• Blood thinners (anticoagulants) if relevant
• Herbal supplements (especially St John’s wort)

Examples of interaction categories (not a complete list)

• TB medicines (e.g., rifampicin/rifapentine, depending on regimen) can lower efavirenz levels and may require careful adjustment.
• Some seizure medicines can affect efavirenz metabolism, requiring monitoring or alternative choices.
• Hormonal contraception: efavirenz may reduce effectiveness of some contraceptive methods. Discuss reliable contraception options with your clinician.
• Herbal supplements: St John’s wort is a well-known interaction risk and is generally avoided with many antiretrovirals.

Because the interaction picture depends on your exact medicines and dose, your healthcare team should check interactions using reliable references.

Safety profile: common and serious side effects

Like all medicines, Sustiva can cause side effects. Many people tolerate efavirenz well, but some effects are more common—especially early in treatment.

Common side effects

• Dizziness
• Nausea
• Sleep disturbance (e.g., vivid dreams)
• Headache
• Fatigue
• Rash (varies from mild to severe)

Some central nervous system effects may reduce after the first couple of weeks. Bedtime dosing can help. If symptoms are severe, persistent, or affecting daily activities, seek medical advice.

Serious side effects: seek urgent medical attention

• Severe rash, blistering, peeling skin, mouth sores, or rash with fever (possible serious skin reactions)
• Liver problems: yellowing of the skin/eyes (jaundice), dark urine, severe abdominal pain, or unusual tiredness
• Severe mental health symptoms: severe depression, suicidal thoughts, hallucinations, or extreme confusion
• Allergic reactions: swelling of face/lips, difficulty breathing

Safety monitoring

Your clinician may monitor:

• Liver function (blood tests)
• Clinical symptoms (rash, mood changes, sleep effects)
• HIV viral load and CD4 counts as part of routine HIV care
• Other tests depending on your overall regimen and health conditions

Pregnancy, breastfeeding and fertility considerations

If you are pregnant, planning pregnancy, or able to become pregnant, it is especially important to discuss efavirenz with your clinician. Efavirenz has pregnancy-related considerations, including potential risks to a developing baby.

• Contraception: Efavirenz may reduce effectiveness of some hormonal contraceptives. Your clinician can recommend reliable contraception methods.
• Breastfeeding: Recommendations depend on local guidance and individual circumstances. Discuss risks and benefits with your healthcare provider.

Kidney and liver considerations

Efavirenz is mainly processed by the liver. If you have existing liver disease or abnormal liver tests, your healthcare team may decide whether efavirenz is appropriate and will monitor you closely.

Seek advice promptly if you develop symptoms suggestive of liver injury.

Recent guidance and treatment context in Australia

HIV treatment guidelines in Australia emphasise combination antiretroviral therapy and individualised selection based on resistance patterns, patient factors, and interaction risk. Over time, many modern regimens have become common due to tolerability and lower interaction burden.

Efavirenz may still be used in certain circumstances where it is suitable for the individual, including:

• When efavirenz-based regimens are already established and well tolerated
• Situations guided by resistance testing and clinician assessment
• When alternative options are unsuitable due to interactions or other factors

Clinical recommendations can change as new evidence emerges. Your HIV care team can confirm whether efavirenz remains an appropriate choice for your situation.

Delivery and availability in Australia

Availability of specific antiretroviral brands and formulations can vary based on supply chains and prescribing practices. If your preferred brand is not available, clinicians may consider clinically equivalent alternatives, depending on your regimen.

For online ordering, delivery typically depends on:

• Stock status at the time of purchase
• Dispensing and dispatch processes
• Delivery address and courier schedules

When ordering medicines online, confirm the following before placing an order:

• Your exact product strength and formulation
• Order and delivery timeframes that meet your treatment schedule
• Packaging integrity and expiry date

Alternative options

If efavirenz is not suitable (for example, due to side effects, interactions, or pregnancy considerations), clinicians may consider other antiretroviral medicines. Alternatives depend on your treatment history and resistance testing results.

Common alternative categories include:

• Other NNRTIs (depending on suitability and interactions)
• Integrase inhibitors (often preferred due to tolerability and potency in many modern regimens)
• Protease inhibitor–based regimens
• Other classes in special circumstances

Discuss with your HIV specialist before switching. Changing therapy can require careful planning to maintain viral suppression and avoid resistance.

Market and legal context for Australia

Antiretroviral medicines in Australia are regulated medicines and are provided through approved supply channels. Public health and clinical guidance supports access to effective HIV treatment for eligible people.

Supply practices may involve pharmacist dispensing and eligibility rules depending on the medicine and circumstances. Always ensure you obtain medicines from reputable, authorised sources.

When to contact a healthcare professional

• New or worsening rash, especially if accompanied by fever or blisters
• Signs of liver issues (yellow eyes/skin, dark urine, severe abdominal pain)
• Severe mood changes, confusion, hallucinations, or suicidal thoughts
• Persistent vomiting, inability to keep medicines down, or symptoms that concern you
• Any planned start/stop of other medicines or supplements

FAQ about Sustiva (Efavirenz)

1) What is Sustiva used for?

Sustiva (efavirenz) is used to treat HIV infection as part of a combination antiretroviral regimen. It helps suppress HIV so that your immune system can recover and viral load remains controlled.

2) How should I take it—morning or night?

Many people take efavirenz at bedtime because it can reduce the impact of early nervous-system side effects. Follow your prescriber and the CMI for your exact schedule.

3) Can I take Sustiva with food?

Food can affect efavirenz levels. High-fat meals may increase exposure and the chance of side effects. Many regimens advise taking efavirenz on an empty stomach or with light food—confirm your instructions with the CMI or your pharmacist.

4) What side effects are common when starting efavirenz?

Common effects include dizziness, nausea, sleep disturbance (like vivid dreams), headache and fatigue. These may lessen after the first few weeks. If they are severe or persistent, contact your healthcare team.

5) Are there serious warning signs?

Yes. Seek urgent medical advice for severe rash (with fever or blistering), signs of liver problems (yellowing, dark urine), or severe mental health symptoms such as hallucinations or suicidal thoughts.

6) Can I drink alcohol while taking Sustiva?

Alcohol may worsen dizziness and drowsiness. It’s safest to avoid heavy drinking, especially during early treatment. If you choose to drink, do so cautiously and avoid driving if you feel affected.

7) What medicines should I avoid or be careful with?

Efavirenz can interact with many drugs, particularly medicines processed by liver enzymes and medicines that affect seizure control, TB treatment, some antidepressants, and hormonal contraception. Always check with a pharmacist before starting new medicines or supplements.

8) Does efavirenz affect contraception?

Efavirenz may reduce the effectiveness of some hormonal contraceptives. Discuss reliable contraception options with your clinician.

9) What if I miss a dose?

Take it when you remember unless it is close to the next scheduled dose. Do not take double doses. If unsure, ask your pharmacist for advice based on your timing and regimen.

10) Is there an alternative if I can’t tolerate Sustiva?

Yes, other antiretroviral options exist. The best alternative depends on your viral suppression status, resistance history, and interaction risk. Discuss options with your HIV specialist.

Conclusion

Sustiva (efavirenz) is an antiretroviral NNRTI used as part of combination therapy for HIV in Australia. It works by blocking HIV reverse transcriptase, helping reduce viral load and support immune recovery. While some people experience side effects—particularly dizziness, sleep disturbance, and rash—many effects can be managed with correct timing, monitoring, and communication with your healthcare team.

If you have questions about dosing timing, food effects, alcohol use, or interactions with other medicines, speak with a pharmacist or your HIV clinician. Taking antiretroviral therapy consistently is one of the most important steps in maintaining long-term HIV control.