Side Effects of PrEP

What are the side effects of PrEP?

Like all medications, it is possible to get side effects from PrEP. However, not everyone gets side effects, and the symptoms and severity will vary from individual to individual. A 2017 medical review shows that less than 10% of people taking PrEP experience side effects.

Factors such as allergies, other medications you are taking and your current state of health can all impact whether or not you get side effects and how severe they are.

Common side effects

These common side effects may affect up to 1 in 10 people:

feeling or being sick
bloating
indigestion
diarrhoea
headache
dizziness or weakness
difficulty sleeping and abnormal dreams
rash

Common side effects usually clear up within a few days. If they do not clear up or are impacting your life, talk to your doctor who can recommend ways to deal with them or suggest alternatives.

Uncommon side effects

Uncommon side effects are rare and may affect up ≥ 1/1,000 to < 1/100 people:

tummy pain (due to inflammation of the pancreas)
anaemia (due to low red blood cell count)
muscle pain or weakness (due to damage to the kidneys)
allergic reaction

Tests taken while you’re on PrEP can show decreased potassium or increased creatinine in your blood, as well as changes in your urine. That’s why getting the recommended tests while taking PrEP is essential to ensure you and your doctor can manage any developing side effects that you may not be aware of.

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Are there any long-term side effects?

Taking PrEP can have long-term side effects for a small number of people, but these are usually extremely rare and reversible when you stop taking the medication.

Kidney function

Taking PrEP regularly can impact kidney function, which is why there are regular tests for kidney function before and during taking PrEP.

Studies have found that the number of people this affects is small and kidney function returns to normal once people stop taking PrEP. The chance of a decline in kidney function is 1.5 times higher if you take PrEP than if you don’t.

These studies also found that those over 50 were more likely to experience a decline in kidney function than younger people. The studies also noted that for some people who experienced a decrease in their kidney function, changing their diet to reduce protein (including reducing protein supplements) helped to improve their function.

Bone density

Taking PrEP can impact your bone health, especially if you already have a loss of bone mass density. Again, the numbers are small. A 2019 review of medical literature estimated it was under 5% of people taking PrEP who experienced a change to their bone density.

Studies show that bone density returns to normal when you stop taking PrEP.

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How long do side effects last?

Most side effects from PrEP clear up within 1 to 2 weeks. Talk to your doctor if they do not clear up or if they make you very uncomfortable.

If you are experiencing longer-term side effects, these are unlikely to clear up without help. Your doctor will discuss your situation and lifestyle and recommend a way to treat these side effects.

In some cases, for example if you are experiencing long-term side effects, doctors may recommend you take PrEP ‘on demand’ rather than daily.

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How to reduce the side effects from PrEP

You can help to reduce the side effects of PrEP by:

allowing time for your body to adjust to taking it
taking PrEP with food
remembering to take PrEP daily
staying hydrated
getting enough sleep
eating simple foods that are not rich or spicy

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Interactions with other medication and recreational drugs

Most commonly-used medications are not known to interact with PrEP, but doctors recommend that you avoid regularly taking ibuprofen, naproxen or aspirin while taking PrEP. These drugs are called non-steroidal anti-inflammatory drugs (NSAIDs) and can impact your kidneys, which can already be affected by PrEP.

You should not take PrEP if you are already taking other medications that include emtricitabine and tenofovir disoproxil or any other antiviral medicines that contain tenofovir alafenamide, lamivudine or adefovir dipivoxil.

It is essential to let your doctor know if you are taking other medication as it can impact both the effectiveness of PrEP and the side effects you experience.

You must tell your doctor if you are taking any of the following:

aminoglycosides (for bacterial infection)
amphotericin B (for fungal infection)
foscarnet (for viral infection)
ganciclovir (for viral infection)
pentamidine (for infections)
vancomycin (for bacterial infection)
interleukin-2 (to treat cancer)
cidofovir (for viral infection)
ledipasvir, sofosbuvir, sofosbuvir, velpatasvir or sofosbuvir, velpatasvir, voxilaprevir (for hepatitis C infection)
didanosine (for HIV infection)

Recreational drugs

Taking recreational drugs at the same time as PrEP can increase your risk of side effects from either PrEP or recreational drugs, especially while your body is getting used to taking PrEP.

Also, it is hard to know precisely what is in recreational drugs, so the combination of PrEP and recreational drugs can create an unpredictable response in your body.

Talk to your doctor about your recreational drug use when they prescribe PrEP. They can advise you on the risks and signs to look out for. There is also helpful information on the impact of different recreational drugs on the Terrence Higgins Trust site.

Remember that recreational drug use can interfere with your sleep and routines, making you more likely to forget to take PrEP.

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When should I go to a doctor about the side effects of PrEP?

Seek urgent medical attention immediately if you experience any of the following:

Severe allergic reaction: symptoms include wheezing, trouble breathing and talking, swelling of the mouth, face, lips, throat and tongue and a rash
Excess lactic acid in the blood (lactic acidosis): symptoms include deep, rapid breathing, stomach pain and feeling and being sick
Infection or inflammation: symptoms include redness, swelling, heat, pain.
Autoimmune disorders: these can occur a long time after starting to take PrEP; symptoms include those of infection as well as muscle weakness, palpitations, tremors or hyperactivity

Always talk to your doctor about less severe side effects if they impact your life or you are worried. Your doctor can advise on managing the side effects or changing the medication if necessary. It is easy to contact your doctor here at Superdrug Online Doctor using your confidential patient account.

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PrEP FAQs

Are there any side effects to stopping PrEP?

There are no known side effects to stopping PrEP, but always talk to your doctor before you stop taking PrEP, so you understand any risks involved.

Is weight gain a side effect of PrEP?

No scientific evidence exists to prove a link between PrEP and weight gain.

People report both weight gain and weight loss when taking medication to prevent or treat HIV, but there is no proven link. Other lifestyle factors and underlying health conditions may cause a weight change. Talk to your doctor to understand your situation better.

Can PrEP damage your kidneys?

PrEP can affect how your kidneys work. The tests you take before and while taking PrEP check how your kidneys are working to make sure you’re safe.

Can PrEP weaken your bones?

PrEP can lead to weaker bones when you take it long-term. This is usually reversed when you stop taking it. The tests involved in taking PrEP are there to monitor bone density so any concerns are picked up quickly.

Does PrEP cause liver problems?

PrEP can cause liver problems, but this is rare. When they do arise, these issues are caused by the fact that PrEP increases the level of enzymes in the liver.

Talk to your doctor if you notice any of the following: