Sustiva (Efavirenz) – Patient Information (UK)
Sustiva is a brand of medicine containing efavirenz, an antiretroviral medicine used to treat HIV (human immunodeficiency virus). This page explains how it works, how to take it safely and effectively, what to expect, and key safety information for people in the United Kingdom.
Please note: HIV treatment should be individualised. Always follow the advice of your HIV specialist or other healthcare professional.
Basic product information
| Product | Active ingredient | Medicine class | Common form (examples) |
|---|---|---|---|
| Sustiva | Efavirenz | NNRTI (Non-nucleoside reverse transcriptase inhibitor) | Capsules or tablets (form depends on availability) |
Efavirenz works as part of an effective combination regimen. It is rarely used alone because HIV can develop resistance when not treated with adequate combination therapy.
How Sustiva works (mechanism of action)
HIV replicates inside human cells. A key step in replication is carried out by an HIV enzyme called reverse transcriptase. This enzyme helps convert HIV’s genetic material into a form the virus can use to multiply.
Efavirenz blocks reverse transcriptase by binding to a specific site on the enzyme (acting as a non-nucleoside reverse transcriptase inhibitor, or NNRTI). When the enzyme is blocked, HIV cannot reproduce effectively. Over time, combination treatment reduces the amount of virus in the body (viral load), allowing the immune system to recover.
Efavirenz does not cure HIV, but it can control the virus and help people live longer, healthier lives.
Pharmacokinetics: how the body handles efavirenz
“Pharmacokinetics” describes absorption, distribution, metabolism, and elimination. Understanding these features helps explain typical dosing schedules and why certain food and medicine interactions matter.
Absorption
- Efavirenz is absorbed from the gut after swallowing a dose.
- Blood levels can be influenced by food—particularly high-fat meals.
- For many people, the medicine is commonly taken in the evening (often at bedtime) to improve tolerability.
Distribution
- Efavirenz distributes widely in the body, including into the central nervous system. This is one reason some people experience nervous system side effects.
Metabolism (breakdown)
- Efavirenz is mainly broken down by liver enzymes, especially CYP450 pathways (notably CYP2B6).
- Genetic differences and liver function can affect efavirenz levels, which may influence both effectiveness and side effects.
Elimination (leaving the body)
- Efavirenz is eliminated mostly via metabolism and excretion.
- It has a relatively long effective duration, which is why once-daily dosing is commonly used (depending on your regimen).
Typical use in HIV treatment
Sustiva (efavirenz) is used to treat HIV infection as part of combination antiretroviral therapy (ART). Combination therapy reduces the risk of the virus developing resistance to any one medicine.
Your clinician will choose a regimen based on factors such as prior HIV treatment history, resistance tests, other medical conditions, and potential interactions with other medicines.
When it may be chosen
- For some adults and certain paediatric situations (depending on local guidance and formulation/age/weight).
- When efavirenz fits the overall regimen and is appropriate for the individual’s interaction profile.
- In patients who can tolerate the usual timing (often evening) to reduce central nervous system effects.
Indications (what it treats)
Efavirenz is indicated for the treatment of HIV-1 infection in combination with other antiretroviral medicines. The exact recommended use (adult vs paediatric) can depend on national guidance, product formulation, and patient age/weight.
It is not a treatment for hepatitis B or C, and it does not treat opportunistic infections on its own. If you have other infections, your clinician will treat them separately.
How to take Sustiva: timing and administration
Typical timing
Efavirenz is commonly taken and often in the evening or at bedtime. This approach can help reduce early side effects such as dizziness, sleep disturbance, vivid dreams, or feeling “high”.
- Take it around the same time each day.
- If you experience troublesome drowsiness or dizziness, ask your healthcare professional if evening dosing is best for you.
- Do not change your schedule without advice.
With or without food
Food—especially high-fat meals—can increase efavirenz exposure and may worsen side effects for some people. Many patients are advised to take efavirenz on a relatively light basis or as directed by their clinician.
A practical approach is:
- Try taking it either with a light snack or as advised for your specific regimen.
- If you notice side effects are worse after meals, tell your healthcare team.
If you miss a dose
- If you miss a dose, take it as soon as you remember on the same day.
- If you are close to the time of your next dose, skip the missed dose and continue your usual schedule.
- Do not take a double dose to make up for a missed one.
Frequent missed doses can increase the risk of virological failure and resistance. If you are having trouble keeping to the schedule, discuss solutions with your healthcare team.
Food interactions: what to watch
The most relevant dietary issue with efavirenz is the effect of food, particularly fat content, on drug levels and tolerability.
- High-fat meals may raise efavirenz levels and increase the chance of central nervous system side effects.
- Some people tolerate efavirenz better when taken with a consistent routine (for example, at bedtime and with a light snack if needed).
If you plan significant diet changes (for example starting a high-fat diet, or following a medically supervised nutritional plan), ask your clinic whether any adjustment is recommended.
Alcohol and medicine interactions
Alcohol
Efavirenz can affect the nervous system (e.g., dizziness, sleep disturbance, changes in mood). Alcohol may increase these effects, leading to stronger impairment, drowsiness, or poor coordination.
- Avoid or limit alcohol, especially when starting treatment or changing the dose.
- If you feel unsteady, do not drive or operate machinery.
Medicine interactions (common categories)
Efavirenz is metabolised by liver enzymes, and it can also influence other medicines that are processed through similar pathways. This can lead to either increased side effects or reduced effectiveness.
Tell your healthcare professional about all medicines and supplements you use, including:
- Prescription medicines (including antibiotics, antifungals, and epilepsy medicines)
- Over-the-counter medicines (including cold/flu products)
- Herbal products, especially St John’s wort (Hypericum perforatum)
- Recreational substances
Examples of interaction concerns
- St John’s wort: may significantly reduce efavirenz levels and risk treatment failure. Avoid unless your clinician specifically advises otherwise.
- Some anti-seizure medicines: may lower efavirenz levels and/or increase toxicity.
- Some medicines used for tuberculosis (TB): may affect levels of efavirenz; regimens often require careful adjustment and monitoring.
- Hormonal contraceptives: may interact; reliable contraception planning is essential.
- Antidepressants and anxiety medicines: may require review if you experience mood changes.
Because interaction profiles depend on the exact medicine, doses, and your liver function, always ask for a medication review.
Recent guidance and UK context (high level)
In the UK, HIV treatment is guided by clinical guidelines and local protocols. Over recent years, many treatment plans have shifted toward regimens with favourable safety and tolerability profiles (for example, some integrase inhibitor-based therapies). However, efavirenz remains an option in specific circumstances when it is appropriate for an individual’s regimen and interaction profile.
Your clinician will consider:
- National guidance and resistance considerations
- Potential side effects, particularly nervous system effects
- Pregnancy and family planning concerns
- Co-existing conditions (liver disease, TB, mental health history)
- Drug–drug interactions with your current medicines
If you are changing from one regimen to another, do not stop or start medicines without a planned transition plan. Stopping ART can allow viral rebound.
Dosage: typical adult and general considerations
Dosing depends on age, body weight (in paediatric use), the specific formulation, and your overall regimen. Your clinician will specify the exact dose for you.
Common adult dosing (general information)
- Efavirenz is typically taken in combination ART regimens.
- Many adult regimens use a dose of 600 mg once daily, but this may differ based on your regimen and clinical context.
If you have liver problems, or if you are taking medicines known to interact strongly, dosing and monitoring may be adjusted.
Duration of treatment
Efavirenz is generally taken as long as it remains part of your effective ART combination. HIV treatment is usually long-term.
Safety profile: what you should know
Like all medicines, efavirenz can cause side effects. Many people experience mild effects during the first couple of weeks, particularly involving the nervous system, which can improve over time.
Common side effects
- Dizziness
- Sleep disturbance (including insomnia)
- Vivid dreams
- Headache
- Nausea
Taking the medicine in the evening may help reduce some central nervous system symptoms.
Less common but important risks
- Rash: report any rash promptly, especially if it is widespread, blistering, or associated with fever.
- Severe psychiatric symptoms (such as severe anxiety, depression, unusual behaviour, hallucinations): seek urgent medical advice if these occur.
- Liver problems: symptoms may include yellowing of the skin/eyes (jaundice), dark urine, severe fatigue, or abdominal pain.
- Allergic reactions: swelling of the face/lips, trouble breathing, or severe skin reactions require urgent help.
Warnings and precautions
- Driving and machinery: efavirenz can cause dizziness or impaired concentration—avoid driving if affected.
- Mental health history: tell your clinician if you have a history of depression, anxiety, bipolar disorder, psychosis, or substance misuse.
- Liver disease: your healthcare team may monitor liver function tests more closely.
- Interactions: review all medicines to reduce the risk of reduced efficacy or toxicity.
Practical use tips (to help you succeed)
- Use a daily routine: choose a consistent time and link it to an existing habit (for example, bedtime).
- Plan for early side effects: if you experience dizziness or vivid dreams, it may settle after the initial period. If it is severe or worsening, contact your clinic.
- Stay consistent with food: if possible, take it with similar meal patterns day to day.
- Keep your medication list updated: include OTC products and supplements for every review.
- Do not stop ART without advice: interruption can lead to viral rebound.
- Follow monitoring appointments: blood tests and clinical review help check efficacy and safety.
- Report symptoms early: especially rash, mood changes, or signs of liver problems.
Alternatives to Sustiva (efavirenz)
Treatment choices depend on individual factors, including resistance testing, previous ART exposure, pregnancy plans, liver function, and drug interactions. Alternatives may include other antiretroviral classes.
Possible alternative regimens (examples)
- Integrase strand transfer inhibitor (INSTI)-based regimens (often used due to strong tolerability and efficacy profiles).
- Other NNRTIs (depending on suitability and interaction profile).
- Protease inhibitor-based regimens (used in some circumstances).
- Fixed-dose combination tablets that simplify daily dosing (availability varies).
If you are considering switching, ask your HIV team about the reason (side effects, interactions, pregnancy planning, or preference) and how to transition safely.
Delivery and availability in the United Kingdom
Availability of HIV medicines can vary by pharmacy stock and procurement routes. In the UK, many antiretroviral medicines are supplied through established healthcare channels. Online pharmacy availability may depend on local licensing, supply agreements, and the specific medicine form and strength.
- If this product is listed, it may be available for delivery within the UK subject to stock levels.
- Dispatch times can vary based on demand and manufacturer supply.
- Storage guidance may apply—keep medicines in line with the product packaging instructions.
- Always check the delivered product name, strength, and form before use.
For accurate availability and delivery estimates, check the product listing on the pharmacy website.
Market and legal context for the UK
Medicines in the UK are regulated and authorised for supply to patients through licensed channels. Efavirenz-containing products are subject to prescribing practices and medicine safety regulations.
Online pharmacies must operate within applicable UK rules for medicines supply, product identification, and patient safety. If a medicine is shown on a site, it should be supplied in line with relevant legal and professional standards.
If you have any concerns about authenticity or suitability, contact the pharmacy’s customer service or speak with your healthcare professional.
FAQ
1) What is Sustiva used for?
Sustiva (efavirenz) is used as part of combination therapy to treat HIV-1 infection.
2) How quickly does it work?
Many people see a reduction in viral load within weeks of effective treatment. The exact timeline varies and is confirmed by blood tests.
3) Why do I take it in the evening?
Efavirenz can cause nervous system side effects (such as dizziness, insomnia, or vivid dreams). Taking it at bedtime can reduce the impact by letting you sleep through part of the peak effect.
4) Can I take it with food?
Food—especially high-fat meals—may affect efavirenz levels and tolerability. Many people are advised to take it as directed, sometimes with a light snack, and to keep routines consistent.
5) Can I drink alcohol while taking Sustiva?
Alcohol may increase drowsiness and dizziness. Limiting alcohol is advised, especially early in treatment. If you feel unsteady, avoid driving or using machinery.
6) What medicines should not be taken together with efavirenz?
Efavirenz interacts with some medicines and supplements. A key example is St John’s wort, which should be avoided. Other interactions can include certain seizure medicines, TB medicines, and some antidepressant/anxiety medicines. Always review your full medication list with a healthcare professional.
7) What should I do 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 miss doses repeatedly, contact your HIV team.
8) What side effects require urgent help?
Seek urgent medical advice if you develop severe rash (especially with fever or blistering), signs of liver problems (jaundice, severe abdominal pain), severe psychiatric symptoms (confusion, hallucinations, severe depression), or signs of allergic reaction (swelling, trouble breathing).
9) Is Sustiva suitable for everyone?
Not necessarily. Suitability depends on your medical history, liver function, mental health history, pregnancy plans, and potential interactions with other medicines.
10) Are there alternative treatments?
Yes. Depending on your situation, your clinician may consider other antiretroviral options such as INSTI-based regimens or other NNRTIs.
Important: This information is designed to help you understand efavirenz (Sustiva). It does not replace personalised advice from your healthcare professional. If you have symptoms or concerns, contact your HIV clinic or pharmacist promptly.
