Taking two or more different
drugs together may result in an alteration in the effectiveness or in the side-effects
of one or more of the drugs. Some drugs should not be taken in combination with
It is important that your
doctor and pharmacist know about all other medicines and drugs that you are
taking – this includes those prescribed by another doctor, over-the-counter
drugs, herbal and alternative treatments, and recreational drugs.
Some drug combinations are
contraindicated – which means you definitely should not take them together.
Reasons for this include serious side-effects, or interactions which make
one or both drugs ineffective or toxic.
Other interactions are less
dangerous, but still need to be taken seriously. Levels of one or both drugs in
your blood may be affected and you may need to change the doses you take.
Your HIV doctor and
pharmacist will check for possible interactions before they prescribe a new
drug for you.
If any other healthcare
professional prescribes or recommends a medicine for you, it’s important that
they know about the drugs you are taking for your HIV. For example, it’s known
that treatments for erectile dysfunction (such as Viagra) can interact with types of anti-HIV drugs that belong to
the drug classes protease inhibitors (PIs) and non-nucleoside reverse
transcriptase inhibitors (NNRTIs). Interactions with protease inhibitors can
increase blood levels of Viagra and
similar drugs, increasing the risk of side-effects.
You also need to tell your
HIV doctor about any drugs you buy over the counter (at a chemist, for example)
or from the internet. Some anti-HIV drugs can interact with antihistamines, asthma
drugs (steroids), treatments for indigestion and statins (drugs that are used
to control cholesterol, or lipid levels). These treatments can either be
prescribed or bought over the counter at high-street chemists.
If you are thinking of using
any other drugs, you should tell your HIV doctor or pharmacist so they can
check for possible interactions and recommend the most suitable treatment. Or,
when you are buying them, you may wish to tell the pharmacist about the
anti-HIV drugs you are taking. High-street chemists often have a private area
for consultations, or you could write the name of the drugs down and hand them
to him or her. If you do need to mention the name of your anti-HIV drugs, it’s
very unlikely that anyone around you will recognise what they are used to
Less is known about
interactions with recreational drugs. But there are potential interactions
between some recreational drugs (for example, ketamine, ecstacy and methamphetamine
[crystal meth]) and some NNRTIs and PIs. If you use recreational drugs, it is
sensible to discuss this with your doctor, HIV pharmacist or other healthcare
Anti-HIV drugs can also
interact with herbal and alternative treatments. In many cases, the
interactions are theoretical, or seen in test-tube studies, and more information
is needed about the likelihood of a real-life effect.
John’s wort, a herbal remedy used to treat anxiety and
depression, lowers blood levels of NNRTIs and PIs.
have indicated that African potato and Sutherlandia may reduce levels of
PIs, NNRTIs and maraviroc (Celsentri)
in the body.
Interactions can also happen
with medicines that are not taken by mouth. For example, ritonavir can interact
with inhalers and nasal sprays containing fluticasone and salmeterol (e.g. Flixotide,
Flixonase, Seretide and Serevent),
causing serious side-effects.
You can take painkillers,
such as paracetamol or ibuprofen (e.g. Nurofen),
when on anti-HIV drugs, unless there are other medical reasons why you
shouldn’t take this sort of drug.
Make sure you tell your clinic doctor and HIV
pharmacist about all the medicines you are taking. This includes
prescribed medicines, medicines you buy from a chemist, herbal or traditional
medicines, and recreational drugs. Also check before taking anything new
(whether you buy it yourself or have it prescribed by a doctor or dentist).