Some anti-HIV medications can occasionally cause allergic reactions, known as hypersensitivity, but this is rare. The anti-HIV medication with the highest risk of an allergic reaction is abacavir (sometimes known as Ziagen, and also found in Triumeq and abacavir/lamivudine).
Abacavir can cause a serious allergic reaction in some people. This is why your doctor will test you for a gene called HLA-B*5701 if you’re thinking about taking abacavir. If the test is negative, it is unlikely (around a 1 in 100 chance) that you will have an allergic reaction. But you should contact your HIV clinic immediately (or hospital emergency department if it’s out of hours) if you begin to feel unwell after you start taking your medication. The reaction can happen at any time while you’re taking abacavir, but it’s most likely to happen in the first six weeks after you start taking it.
The most common symptoms are high temperature (fever) and skin rash, but you might also:
Other possible symptoms include pains in your joints or muscles, swelling, shortness of breath, sore throat, cough, occasional headaches, eye inflammation (conjunctivitis), mouth ulcers, low blood pressure, and tingling or numbness in your hands or feet.
A very rare allergic reaction has also been reported in some people using other anti-HIV drugs, including:
This can cause a severe rash, called Stevens-Johnson syndrome. See your HIV clinic immediately (or hospital emergency department if it’s out of hours) if you develop a rash and you have any of the other following symptoms:
If you have this sort of reaction, you should not take the drug which caused it again in the future. Other anti-HIV medications can rarely cause allergic reactions too. This means it’s important that you tell your doctor as soon as possible if you develop these symptoms.
