Flu-like symptoms after a zoledronic acid infusion

Many people feel as though they are coming down with flu a day or so after their first zoledronic acid drip. They may have a raised temperature, chills or shivering, aches in the bones, muscles and joints, a headache, tiredness and sometimes feeling sick. Doctors call this an acute phase reaction. It happens because zoledronic acid briefly activates certain immune cells in the blood, which release chemical messengers that cause inflammation and fever. It is not an allergy and not an infection, and it does not mean the medicine is harming you. The reaction is most common after the first dose, affecting a sizeable share of people, and becomes much less likely with later doses, because the immune response settles. It usually starts within a day to three days of the drip and lasts one to three days. Rest, plenty of fluids and paracetamol usually ease it, and some teams suggest taking paracetamol around the time of the drip to lessen symptoms. Anti-inflammatory painkillers such as ibuprofen can affect the kidneys, so ask before using them. The important exception is when you are also having chemotherapy or other treatment that lowers white cells. In that situation a fever must be treated as a possible infection until proven otherwise, so contact your team straight away rather than assuming it is the zoledronic acid.

It is common and short-lived

Most often after the first dose, settling within a few days.

Simple measures help

Rest, fluids and paracetamol are usually enough.

Fever on chemotherapy is different

If your counts may be low, call your team about any fever.

The reaction is well understood, but it cannot always be predicted or fully prevented.

It cannot be predicted

There is no test to tell who will react, although it is less common in people who have had bisphosphonates before.

Prevention is partial

Paracetamol around the time of the drip may lessen symptoms but does not always stop them.

Other causes are possible

Fever and aches can also come from infection or other treatments, which is why some situations need checking.

What this page cannot tell you

It cannot decide whether your fever is safe to manage at home. If in doubt, contact your team.

Many people worry about their next drip after a rough first experience. The outlook is usually reassuring.

Later doses are gentler

The reaction is much less likely and usually milder with second and later doses.

Tell your team how it went

They may suggest paracetamol before the drip or a slower infusion next time.

It is rarely a reason to stop

Because it is short-lived, most people continue treatment without difficulty.