Sustiva (Efavirenz) — Patient-Friendly Medicine Information (UK)
Sustiva is a brand of efavirenz, a medicine used as part of combination treatment to help control HIV-1 (human immunodeficiency virus type 1). This page explains how Sustiva works, how it is taken, important food and alcohol considerations, safety information, and where to find up-to-date UK guidance.
Important: HIV treatment works best when medicines are taken consistently. Always follow the advice given by your healthcare professional and read the patient information leaflet supplied with your medicine.
Basic product information
| Item | Details |
|---|---|
| Medicine name | Sustiva (efavirenz) |
| Active ingredient | Efavirenz |
| Medicine class | Antiretroviral (NNRTI: non-nucleoside reverse transcriptase inhibitor) |
| Typical use | Treatment of HIV-1 as part of combination therapy |
| How it’s taken | Usually once daily by mouth |
| Common UK availability | Brand and/or generic efavirenz may be available depending on supply |
What Sustiva is used for
Sustiva is used to treat HIV-1 infection in adults (and in some cases children/adolescents depending on local guidance and product characteristics) as part of a combination anti-HIV regimen.
It helps reduce the amount of HIV in the body. When used correctly with other HIV medicines, it can:
- Lower “viral load” to very low or undetectable levels
- Help protect the immune system (increase/maintain CD4 cells)
- Reduce the risk of HIV-related illnesses
How it works (mechanism of action)
Efavirenz belongs to the class of medicines called NNRTIs (non-nucleoside reverse transcriptase inhibitors). HIV needs an enzyme called reverse transcriptase to copy itself inside cells. Efavirenz works by:
- Binding to reverse transcriptase and changing its shape
- Stopping the enzyme from working
- Helping prevent new HIV copies from being made
Because HIV can develop resistance if treatment is not effective, efavirenz is typically used alongside other antiretroviral medicines that work in different ways.
Pharmacokinetics (how the body handles efavirenz)
“Pharmacokinetics” describes how efavirenz is absorbed, distributed, metabolised, and eliminated.
- Absorption: Efavirenz is absorbed after oral dosing. Blood levels may be affected by food intake (especially meals with higher fat content).
- Distribution: It distributes widely through the body. Efavirenz crosses into tissues and reaches active sites.
- Metabolism: Efavirenz is mainly broken down by liver enzymes (notably CYP-related pathways).
- Elimination: Metabolites are cleared primarily through the liver and kidneys/bile pathways. Efavirenz has a relatively long half-life.
- Practical implication: Because it stays in the body for a long time, occasional missed doses may be partially “buffered,” but frequent missed doses increase the risk of treatment failure and resistance.
Typical use and dosing (how to take Sustiva)
Efavirenz is generally taken as part of a once-daily combination regimen. Exact dosing for you may differ depending on age, body weight, other medicines, and your treatment history.
Typical adult dosing (general information)
A commonly used adult dose is one 600 mg tablet once daily in combination therapy. Your clinician may adjust the regimen depending on your situation.
For children, dosing may be based on body weight and/or product availability. If you are seeking information for a child, consult the clinician/pharmacist for the correct strength and schedule.
Timing: when to take it
Many people are advised to take efavirenz at bedtime. This can help reduce potential side effects such as dizziness, unusual dreams, or sleep disturbances, which often occur early in treatment.
- Best practical approach: Take your dose about the same time each day.
- If starting treatment: Taking it at bedtime may make early side effects easier to manage.
How to swallow
Follow the instructions in your leaflet for how to take your specific tablet or formulation. Swallow tablets with water. Do not crush or break unless your product information specifically allows it.
Food interactions (what to eat and drink)
Efavirenz exposure can increase when taken with higher-fat meals. For some people this can increase the likelihood of side effects, particularly those affecting the nervous system.
General advice:
- Try to take Sustiva on an empty stomach if you have been advised to do so (for example, with little or no food).
- If your clinician/pharmacist has recommended taking it with food, follow that advice precisely.
- Avoid large, high-fat meals around the time you take your dose unless you have been told otherwise.
If you notice side effects after meals, discuss timing and food patterns with your healthcare professional—adjusting meal timing can help.
Alcohol and medicine interactions
Alcohol
Alcohol can make certain side effects of efavirenz feel worse, especially:
- Dizziness
- Sleep disturbance
- Impaired concentration
If you choose to drink alcohol, consider keeping amounts low and avoid drinking at times when you might be impaired by the medicine (especially soon after starting). If you have a history of heavy alcohol use or liver problems, ask your clinician for specific advice.
Medicine interactions (very important)
Efavirenz can interact with several medicines because it affects liver enzymes and drug transport systems. Interactions may either reduce HIV treatment effectiveness or increase risk of side effects.
Tell a healthcare professional about all medicines you take, including:
- Over-the-counter medicines and cold/flu products
- Herbal supplements (especially St John’s wort)
- Antacids and stomach medicines
- Antifungals and antibiotics
- Anticonvulsants
- Heart rhythm medicines
- Diabetes medicines
- Hormonal contraception
Examples of interactions to be aware of:
- St John’s wort: may lower efavirenz levels and lead to treatment failure; usually should be avoided.
- Some seizure medicines: may change efavirenz levels and vice versa.
- Some antibiotics/antivirals: may increase or decrease efavirenz exposure.
- Hormonal contraception: efavirenz can reduce the effectiveness of some methods—effective contraception planning is essential.
This is not a complete list. Your pharmacist can help check specific interactions if you provide your medicines and doses.
Indications and important considerations
Efavirenz is indicated as part of combination therapy for HIV-1 infection. Its suitability depends on treatment history and other factors such as drug resistance, co-existing conditions, and interaction potential.
Key points that may affect whether Sustiva is appropriate:
- Drug resistance: Previous HIV treatments and resistance testing can guide which regimen is most effective.
- Co-existing medical conditions: Especially liver problems or kidney disease.
- Mental health or neurological history: Some people experience nervous system side effects.
- Pregnancy plans: Efavirenz may be associated with specific risks during pregnancy; discuss carefully with clinicians.
- Other medicines you take: Interaction potential can be significant.
Safety profile (what to watch for)
Like all medicines, efavirenz can cause side effects. Many people experience mild effects early on, while others may have more serious reactions. If you feel unwell or something seems unusual, seek medical advice promptly.
Common side effects
- Dizziness
- Sleep disturbances (including insomnia)
- Unusual dreams
- Headache
- Nausea
- Fatigue
- Rash (often appears early)
These effects often lessen after the first few weeks for many people, particularly when the dose is taken at bedtime.
Serious side effects — seek urgent help
Get urgent medical advice if you develop:
- Signs of severe allergic reaction: swelling of face/lips, difficulty breathing, severe rash
- Severe rash, blistering, or peeling skin
- Severe mood changes: suicidal thoughts, severe depression, confusion, hallucinations
- Signs of liver problems: yellowing of eyes/skin (jaundice), dark urine, severe abdominal pain, persistent vomiting
- New or worsening symptoms that concern you
Long-term safety notes
With long-term HIV treatment, your clinician will regularly monitor:
- Viral load and immune markers
- Liver function through blood tests
- General health parameters relevant to your overall regimen
Practical use tips for getting the best results
- Take consistently: Aim for the same time every day.
- Bedtime dosing: If advised, take at bedtime to reduce nervous system side effects.
- Watch food patterns: Avoid large high-fat meals around dosing unless instructed otherwise.
- Keep a routine: Link dosing to a consistent daily event (e.g., brushing teeth before sleep).
- Do not stop or change medicines: Stopping or changing can allow HIV to replicate and resistance to develop.
- Report new symptoms early: Early discussion can prevent problems from worsening.
- Check interactions: Before starting new OTC medicines or herbal products, ask your pharmacist.
If you miss a dose
If you miss a dose, take it as soon as you remember on the same day, unless it is close to the time of the next dose. Do not take a double dose to make up for a missed dose. If you are unsure, ask your pharmacist or clinician for advice based on your schedule.
Missed doses, adherence and resistance (why it matters)
Efavirenz is effective when taken correctly as part of a combination regimen. Missed doses can lead to incomplete suppression of HIV and increase the chance of drug resistance.
- Consistency: Try not to skip doses.
- Plan ahead: Keep an emergency supply where possible.
- Use reminders: phone alarms, pill boxes, or calendars can help.
Alternative options to consider
There are different antiretroviral options for HIV treatment. The most appropriate alternative depends on:
- Your viral load and CD4 count
- Previous treatments and resistance results
- Other health conditions
- Potential drug interactions
- Pregnancy status or planning
In the UK, many people use modern once-daily regimens that may have different side effect profiles and interaction characteristics. Examples of antiretroviral classes include:
- Integrase strand transfer inhibitors (INSTIs)
- Other NNRTIs (depending on suitability)
- NRTI backbones used in combination
Discuss options with your HIV specialist team. They can review whether switching is beneficial and safe for your particular situation.
Market and legal context for the UK
In the United Kingdom, medicines including efavirenz are regulated by the Medicines and Healthcare products Regulatory Agency (MHRA). Healthcare services often follow UK clinical pathways issued by national bodies and specialist networks.
HIV medicines are typically supplied through approved routes, and pharmacies must follow relevant UK medicines supply regulations, including patient safety checks and appropriate sourcing.
This information is provided to help patients understand the medicine. It is not a substitute for advice from a healthcare professional.
Recent guidance and monitoring (UK context)
UK HIV guidance is periodically updated to reflect new evidence, drug developments, and safety information. When planning or reviewing HIV treatment, clinicians typically consider:
- Current national HIV treatment guidelines
- Local protocol recommendations for regimen choice
- Resistance testing results where appropriate
- Drug–drug interaction review
- Adherence support strategies
If you would like, you can ask your clinic or pharmacist where to find the most current UK HIV treatment guidance used in your area. For many patients, the HIV specialist team will already have guidance integrated into prescribing decisions.
Delivery and availability (UK)
Availability can vary by supplier and time. When ordering medicines through a reputable UK pharmacy, delivery usually depends on:
- Stock levels at the time of order
- Whether the product is brand or generic
- Dispensing and safety checks
- Delivery address and courier service
Typical online pharmacy services offer options such as standard and express delivery (subject to availability and local regulations). You can usually view estimated delivery times at checkout.
If a product is temporarily unavailable, many pharmacies can offer an alternative equivalent option where permitted and appropriate—your pharmacist can advise what is suitable for you.
FAQ
1) What is Sustiva used for?
Sustiva (efavirenz) is used in combination HIV therapy to treat HIV-1 infection. It helps suppress HIV by blocking reverse transcriptase.
2) How should I take it — morning or night?
Many people are advised to take efavirenz at bedtime to reduce early nervous system side effects such as dizziness or sleep disturbances. Follow your clinician’s specific instructions.
3) Can I take Sustiva with food?
Food can affect efavirenz blood levels. Guidance may vary based on your regimen and leaflet instructions. As a general principle, avoid large, high-fat meals around the time you take your dose unless your clinician has told you otherwise.
4) What happens if I miss a dose?
Take it when you remember on the same day unless it is close to the next dose. Do not take a double dose. If you are unsure, ask your pharmacist or clinic for advice.
5) Is alcohol safe with efavirenz?
Alcohol may worsen dizziness or sleep/mood-related side effects. If you drink, keep amounts low and avoid drinking when you might be affected. Seek advice if you have liver problems or a history of alcohol misuse.
6) What medicines interact with efavirenz?
Efavirenz can interact with several medicines, including some herbal products (notably St John’s wort) and a range of prescription medicines. Tell your pharmacist about everything you take so they can check compatibility.
7) What side effects are most common?
Common side effects include dizziness, unusual dreams, sleep disturbance, headache, nausea, fatigue, and rash—particularly early in treatment.
8) When should I seek urgent medical help?
Seek urgent help if you develop severe rash or signs of allergic reaction, severe mood changes, confusion or hallucinations, or symptoms that may indicate liver problems (such as yellowing eyes/skin).
9) Who should be extra careful when using efavirenz?
People with liver disease, a history of significant mental health issues, pregnancy/planning pregnancy, and those taking multiple medicines with possible interactions should discuss safety carefully with their healthcare team.
10) Are there alternatives to Sustiva?
Yes. HIV treatment regimens are designed to be individualised. Your clinician can discuss other antiretroviral options, considering effectiveness, resistance patterns, side effects, and interactions.
