Medication Information Leaflet

What is this medication for?

Efavirenz is an antiretroviral medication used for treating human immunodeficiency virus (HIV) infection. It works by preventing the virus from reproducing and hence reducing the amount of virus in your body. This increases the CD4 cell count in your body. CD4 cells are a type of immune cells that help your body fight off infections.

Efavirenz is not a cure for HIV infection. It must be taken consistently every day with your other antiretroviral medications to slow the progression of the disease.

How should I take/use this medication?

• Efavirenz should be taken at bedtime at least 2 hours after your last meal of the day. This is to minimize side effects from the medication.
• It is important that you take this medication daily at a regular time.
• Do not miss any doses as this may make the medication less effective.
• Do not stop taking your medication without consulting healthcare professional. Stopping medication may result in worsening of the infection.

What should I do if I forget to take/use this medication?

If you forget to take a dose, take it as soon as you remember. Then take your next dose at the usual time. Do not take two doses to make up for the missed dose.

What precautions should I take?

Inform your healthcare professional if:

• You are allergic to this medication or any of the other ingredients of this medication.
• You are pregnant, planning to become pregnant, or breastfeeding.
• You are taking any other medications, including supplements, traditional medications and herbal remedies.
• You develop any depression related symptoms such as constantly feeling sad or feeling a sense of hopelessness, or you develop thoughts or harming yourself.

What are some common side-effects of this medication?

• Drowsiness, insomnia, dizziness, abnormal dreams
  • Take the medication at bedtime on an empty stomach to help minimize these side effects. These side effects may also resolve on their own after 2 to 4 weeks. Consult your doctor if they persist and/or bother you.
  • Do not drive or do any tasks that require you to be alert if you experience drowsiness or dizziness with the medication.
  • Avoid consuming alcohol with the medication as it may worsen any drowsiness or dizziness that you experience with the medication.
• Hot flushes and intermittent rashes
  • These usually resolve on after a while. Consult your doctor if they persist and/or bother you. Staying in a cool environment and wearing lightweight clothing may also help.
• Increase in cholesterol levels
  • Your doctor will monitor your cholesterol levels periodically through blood tests.
  • Maintaining a healthy diet and regular exercise can also help improve cholesterol levels.

What are some rare but serious side-effects that I need to seek medical advice immediately?

Stop the medication and consult your doctor immediately if you experience any of the following symptoms of a drug allergy:

• Swollen face/eyes/lips/tongue
• Difficulty in breathing
• Itchy skin rashes over your whole body

Consult your doctor or seek professional help immediately if you experience persisting symptoms such as nervousness or feeling sad, or you have thoughts of hurting yourself.

This medication may affect the liver of some patients. Do consult your doctor if you experience any signs of liver problem such as:

• Yellowing of the skin and eye white
• Dark-coloured urine
• Light-coloured stools
• Lower abdominal pain
• Nausea
• Loss of appetite

What food or medication should I avoid when I take this medication?

• High-fat or high-caloric meals can increase the absorption of the medication. This may increase the risk of side effects of drowsiness, insomnia, dizziness, abnormal dreams. Take the medication on an empty stomach if you do experience these side effects.
• Inform your healthcare professional if you are taking any of the following medications:
  • Carbamazepine for seizure control or other conditions
  • Hormonal contraceptives or gender-affirming therapy
  • Antifungal medications such as Itraconazole, Ketoconazole, Posaconazole, Voriconazole
  • Hepatitis C medication Epclusa
  • Tuberculosis medication Rifabutin, Rifampicin

How should I store this medication?

Store in a cool and dry place, away from direct sunlight. Keep this medication away from children.

How should I throw away this medication safely?

Pack the medication into a bag and bring it back to the pharmacy where you received the medication from.

Disclaimers

Please take note that the above is not a complete list of all possible side effects. If you have any concerns about your medication or if you have other side effects that you think are caused by this medication, please consult your doctor or pharmacist.

If you take more than the recommended dose, please seek medical advice immediately. The information provided on this page does not replace information from your healthcare professional. Please consult your healthcare professional for more information.

This article is jointly developed by members of the National Medication Information workgroup. The workgroup consists of cluster partners (National Healthcare Group, National University Health System and SingHealth), community pharmacies (Guardian, Unity and Watsons) and Pharmaceutical Society of Singapore. The content does not reflect drug availability and supply information in pharmacies and healthcare institutions. You are advised to check with the respective institutions for such information.

Last updated on August 2023