A pharmacokinetic 'booster' for certain HIV medicines
Cobicistat
A 'booster' medicine that raises the levels of certain HIV medicines but has no antiviral effect itself.
What is Cobicistat?
Cobicistat is a pharmacokinetic 'booster'. It has no effect on HIV itself; instead, it is given alongside certain HIV medicines to slow how quickly the body breaks them down, keeping their levels high enough to work well. The most important things to know are that, because it blocks an enzyme the body uses to clear many drugs, it interacts with a very large number of other medicines, and it raises the blood creatinine reading (a measure used for the kidneys) without actually damaging the kidneys. It is always taken together with the HIV medicine it is boosting, never on its own, and it is supervised by an HIV specialist.
Education and reference only. This is a plain-language guide to Cobicistat — it deliberately contains no doses. Doses depend on the person, the brand and the reason for treatment, and belong with your prescriber. Always check the BNF, the product labelling (SmPC) and follow medical advice.
What it is
Cobicistat is an HIV-related medicine that works as a 'booster', also called a pharmacokinetic enhancer. On its own it does nothing against HIV; its only job is to raise and maintain the levels of certain other HIV medicines so they work effectively at convenient doses. It does this by slowing down the body's breakdown of those medicines. It is always taken together with the HIV medicine it boosts, often combined into a single tablet, and never used by itself. It is taken by mouth, every day, under the supervision of an HIV specialist team.
How it works
The body uses enzymes, particularly one called CYP3A, to break down many medicines. Some HIV medicines are cleared so quickly by this enzyme that they would not stay at effective levels on their own. Cobicistat blocks this enzyme, slowing the breakdown of the HIV medicine it is paired with, so its level stays high enough to keep the virus under control. Because cobicistat blocks an enzyme that handles a huge range of medicines, it can also raise the levels of many other drugs, which is why interactions are such an important consideration. It has no direct effect on the virus itself.
Company & origin
Originated / developed by: Specialist manufacturer.
An HIV-related medicine used in the UK as a 'booster' to raise the levels of certain HIV medicines; it has no antiviral effect of its own.
Practical use
How to take Cobicistat
General, dose-free guidance — always follow your prescriber's and the leaflet's specific instructions.
- Take it every day together with the HIV medicine it boosts, exactly as prescribed; never take it on its own.
- Take it with food if advised, and at about the same time each day along with the medicine it supports.
- Give your team a full list of all your other medicines, including over-the-counter and herbal products, as it interacts with many.
- Do not start any new medicine, including ones bought without prescription, without checking with your HIV team first.
- Do not be alarmed by a rise in your creatinine reading; your team knows it can raise this without harming the kidneys.
Weighing it up
Advantages & disadvantages of Cobicistat
Advantages
- Boosts the levels of certain HIV medicines so they work effectively at convenient doses.
- Can be combined with the medicine it supports in a single daily tablet.
- Helps keep HIV treatment simple and effective when taken consistently.
Disadvantages
- Has no effect on HIV itself and must always be taken with the medicine it boosts.
- Interacts with a very large number of other medicines.
- Raises the blood creatinine reading, which can look like a kidney change even though it is not true damage.
Practical use
Good to know
The two most important things to understand about cobicistat are interactions and the creatinine effect. Because it blocks an enzyme the body uses to break down a very large number of medicines, it can raise (or sometimes lower) the levels of many other drugs, including common ones, which can lead to serious interactions; for this reason a complete and up-to-date medicines list, including anything bought over the counter or herbal, is essential. The second point is that cobicistat raises the blood creatinine reading, which is a number often used to estimate kidney function, but it does this without actually harming the kidneys; the team understands this and interprets the results accordingly. It is also vital to know that cobicistat is only a booster: it must always be taken with the HIV medicine it supports, every day, and it does nothing against HIV on its own.
Who should not take it / use with caution
- People who have had a serious allergic reaction to cobicistat should not take it.
- It must not be combined with certain medicines that become dangerous when their levels are raised; the team checks this carefully.
- It is used with caution in people with kidney or liver problems, under specialist guidance.
Monitoring
- Checking kidney-related blood tests, interpreting the creatinine reading in light of cobicistat's effect.
- Reviewing all other medicines regularly for possible interactions.
- Checking that HIV treatment overall is keeping the virus suppressed.
Side effects
- A rise in the blood creatinine reading, which reflects how it works rather than true kidney damage.
- Nausea or other mild stomach upset in some people.
- Effects arising mainly from interactions with other medicines whose levels it raises.
Key interactions
- It interacts with a very wide range of medicines, so a full and current medicines list is essential.
- It can raise the levels of many drugs to harmful levels, so some combinations must be avoided.
- Some medicines and herbal products, such as St John's wort, can stop it and its partner medicine working.
Available as: Tablets taken by mouth, often combined with the HIV medicine it boosts.
Answers
Cobicistat: frequently asked questions
What does cobicistat do?
It is a 'booster' that raises the levels of certain HIV medicines by slowing how quickly the body breaks them down; it has no effect on HIV itself.
Can I take it on its own?
No. It must always be taken together with the HIV medicine it boosts, as it does nothing against the virus by itself.
Why has my creatinine gone up?
Cobicistat can raise the blood creatinine reading, often used to estimate kidney function, without actually damaging the kidneys; your team interprets this correctly.
Why does my team need my full medicines list?
It interacts with a very large number of medicines, raising or lowering their levels, so a complete list helps avoid dangerous combinations.
Is it an HIV medicine?
It is used in HIV treatment, but only as a booster for other HIV medicines; it has no antiviral effect of its own.
The wider class
About Pharmacokinetic enhancer (HIV booster)
Cobicistat belongs to the pharmacokinetic enhancer (hiv booster) class. For how the class as a whole works, its shared safety principles and monitoring, see the full guide.
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Authoritative sources
- BNF
- NICE CKS
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