Key points
- In the UK, the recommended PEP medications of emtricitabine/tenofovir and raltegravir are generally well tolerated by most people.
- Some people have short-term problems such as being sick, feeling sick, diarrhoea, and headaches.
- Drug interactions can happen if you take PEP with other medications.
Post-exposure prophylaxis (PEP) is a way of preventing HIV infection. It involves using a four-week course of the same drugs used to treat HIV, which you take very soon after you may have been exposed to the HIV virus.
What are the most common PEP drugs?
Each course of PEP contains three anti-HIV drugs. It is important to take all three drugs for PEP to be effective.
Two of these medications are usually from a class of drugs known as nucleoside reverse transcriptase inhibitors (NRTIs). This is often tenofovir (tenofovir disoproxil or tenofovir alafenamide) and emtricitabine. These two medications are often taken together in a single pill.
A third medication, usually from the integrase inhibitor class, may be taken separately. Often this will be raltegravir or dolutegravir. If the third medication is bictegravir, then all three drugs are combined in one pill.
Sometimes a protease inhibitor is used instead of an integrase inhibitor, such as darunavir or atazanavir.
In the UK, the recommended PEP regimen is tenofovir disoproxil, emtricitabine, and raltegravir once a day for at least 28 days.
The drugs used in PEP today are less likely to cause side effects than in the past. They also have fewer potential drug-drug interactions.
What are the other PEP options?
Another type of drug called a ‘boosted protease inhibitor’ may also be used if an integrase inhibitor isn’t right for you (for example, if you have certain health conditions).
Boosted protease inhibitors consist of one main protease inhibitor taken with a small amount of another protease inhibitor called ritonavir. This low dose of ritonavir ‘boosts’ and maintains levels of the main protease inhibitor in your body.
Boosted protease inhibitors that may be prescribed include lopinavir, darunavir, or atazanavir.
Drug-drug interactions are more likely with protease inhibitors. There is more information about drug-drug interactions further down the page.
What are the side effects of PEP?
Many people will take PEP without having any side effects. However, all medication can cause side effects. On this page we talk about common side effects of the drugs used in PEP. Common side effects are ones that happen to more than 1 in 100 people.
However, just because symptoms are common, it doesn’t mean you have to put up with them. If side effects are making it hard for you to take your medication, you should speak to your doctor. It’s really important that you finish the whole course.
It’s also important to know that most of the information we have about side effects come from HIV-positive people taking the same medications over many years as HIV treatment.
Some common side effects haven't been included as they are not likely to happen in a month.
There are some side effects that are common for all types of PEP medication listed below. These are:
- being sick (vomiting)
- feeling sick (nausea)
- diarrhoea
- headache
- rash.
On this page, other common side effects are listed for each drug. The most common medicines and their side effects are listed first, with less common medicines listed further down the page.
Bictegravir (Biktarvy)
Common side effects of bictegravir include:
- depression
- dizziness
- strange dreams
- tiredness
- tummy (abdominal) pain.
For more information, read our factsheet on bictegravir.
Dolutegravir (Tivicay)
Common side effects of dolutegravir include:
- depression
- dizziness
- feeling very tired (fatigue)
- itching
- trouble sleeping (insomnia) and strange dreams
- tummy (abdominal) pain.
- wind (flatulence).
Rarely, dolutegravir can cause a hypersensitivity (allergic) reaction. If you develop a rash with other symptoms, such as a fever, seek medical advice.
For more information, read our factsheet on dolutegravir.
Emtricitabine with tenofovir (Truvada or Descovy)
Common side effects of emtricitabine with tenofovir are:
- allergic reactions (such as wheezing, swelling, or feeling light-headed)
- bloating
- dizziness
- feeling weak
- pain
- trouble sleeping (insomnia) and strange dreams
- tummy (abdominal) pain
- wind (flatulence).
There are two types of tenofovir. Tenofovir disoproxil (found in Truvada) can affect the kidneys, so you might be given tenofovir alafenamide (found in Descovy) if you already have severe kidney disease.
For more information, read our factsheets on Truvada and Descovy.
Lamivudine
Common side effects of lamivudine include:
- feeling less hungry than normal
- feeling very tired (fatigue)
- tummy (abdominal) pain.
For more information, read our factsheet on lamivudine.
Raltegravir (Isentress)
Common side effects of raltegravir include:
- bloating
- depression
- dizziness
- feeling less hungry than usual
- feeling very tired (fatigue)
- feeling weak
- fever
- indigestion
- trouble sleeping (insomnia) and strange dreams
- tummy (abdominal) pain
- vertigo
- wind (flatulence).
Rarely, raltegravir can cause a hypersensitivity (allergic) reaction. If you develop a rash with other symptoms, such as a fever, seek medical advice.
For more information, read our factsheet on raltegravir.
Taking raltegravir and emtricitabine/tenofovir together
There have been occasional reports of muscle-related side effects from people taking the combination of emtricitabine/tenofovir and raltegravir.
These included reports of myalgia (muscle pain), and rhabdomyolysis (muscle damage that can lead to renal complications). If you have a history of these conditions, or you are using other medications associated with these conditions (such as statins), you might be monitored more closely or offered an alternative drug.
Less common PEP medications
These medicines might be prescribed to you if you’re unable to take more common PEP combinations.
Atazanavir with ritonavir (Reyataz and Norvir)
Common side effects of atazanavir include:
- indigestion
- tiredness
- tummy (abdominal) pain
- yellowing of the skin and/or eyes (jaundice).
Yellowing skin or eyes is fairly common when taking atazanavir, especially when you first start the drug. Although this can look scary, it is harmless and does not mean that your liver is damaged or not working in any way.
Rarely, atazanavir can cause a hypersensitivity (allergic) reaction. If you develop a rash with other symptoms, such as a fever, seek medical advice.
For more information, read our factsheet on atazanavir.
Darunavir with ritonavir (Prezista and Norvir)
Common side effects of darunavir include:
- bloating
- dizziness
- drowsiness
- indigestion
- itching
- numbness
- peripheral neuropathy (damage to nerves in the hands or feet causing tingling or pain)
- tiredness
- trouble sleeping (insomnia)
- tummy (abdominal) pain
- weakness
- wind (flatulence).
For more information, read our factsheet on darunavir.
Elvitegravir (Stribild or Genvoya)
- bloating
- constipation
- dark skin patches (often starting on the hands or soles of feet)
- dizziness
- feeling less hungry than normal
- feeling very tired (fatigue)
- indigestion
- itching
- trouble sleeping (insomnia) and strange dreams
- weakness
- wind (flatulence).
For more information, read our factsheets on Stribild and Genvoya.
Lopinavir with ritonavir (Kaletra)
Lopinavir (200mg) and ritonavir (50mg), taken twice daily, often causes diarrhoea and other gastrointestinal issues.
Other common side effects of lopinavir with ritonavir are:
- allergic reaction including swelling
- anxiety
- bloating
- dizziness
- erectile dysfunction
- feeling less hungry than normal
- haemorrhoids
- heartburn and indigestion
- high blood pressure
- itching
- menstrual disorders
- muscle pain
- pancreatitis
- peripheral neuropathy (damage to nerves in the hands or feet causing tingling or pain)
- problems with your breathing system such as sinus or throat infections, cough, sore throat, or runny nose
- skin infections
- tiredness
- trouble sleeping (insomnia)
- tummy (abdominal) pain
- weakness
- wind (flatulence).
For more information, read our factsheet on lopinavir/ritonavir.
How long do PEP side effects last?
Side effects usually appear soon after starting PEP as the body adjusts to the new medications. Side effects often decrease, become manageable, or go away completely after a few days or weeks.
Can I take other medications while on PEP?
It depends. PEP can cause drug interactions with other medications. A drug interaction is when one medicine affects how another medicine works. For example, taken together, one medicine may increase the side effects of another medicine.
For example, antacids, multivitamins, and iron supplements should be avoided if you’re taking raltegravir.
It is important to tell your doctor or pharmacist about all other medicines and drugs that you are taking. This includes those prescribed by another doctor, over-the-counter medicines (including inhalers and nasal sprays), supplements, herbal and alternative treatments, and recreational drugs.
With all PEP regimens, your doctor or pharmacist should check for drug-drug interactions.
The University of Liverpool provides an online tool to check for interactions between anti-HIV drugs, other medications and recreational drugs. You enter the names of the medication you are taking and the results are provided with a traffic-light system: if the result is red or orange, it’s worth checking with your doctor or pharmacist. If it’s green, there shouldn’t be any problem. Visit www.hiv-druginteractions.org/checker.