Steroids and High White Blood Cell Count: Is It the Medicine or an Infection?

Yes. Corticosteroids, such as prednisone and prednisolone, are a well-known cause of a raised white blood cell count. Cleveland Clinic and the American Academy of Family Physicians both list corticosteroids among the medicines associated with leukocytosis, the medical term for a high white cell count, and MedlinePlus lists certain steroids as a cause of a high count.

The rise is usually in neutrophils, the most plentiful type of white blood cell. But a high count on steroids can also come from the condition being treated, or from an infection. This guide explains how clinicians think about that question. It cannot tell you which applies to you.

MedlinePlus says prednisone may lower the ability to fight infection, and advises calling your doctor right away for a sore throat, fever, chills, cough or other signs of infection. Do not assume a high white cell count is just the steroid if you feel unwell.

Cleveland Clinic advises calling emergency services or going to an emergency department for the signs below. Seek emergency help, too, if you are very unwell, confused or getting rapidly worse.

• Difficulty breathing.
• Chest pain.
• Signs of a stroke.
• Tingling in the arms, legs or abdomen.
• Sudden back pain.
• Bleeding that does not stop.

Many neutrophils normally sit along the walls of blood vessels or wait in storage rather than circulating freely. The American Academy of Family Physicians explains that drugs, infection, inflammation and other triggers can release these stored cells into the circulating blood, which can raise the count within hours. Glucocorticoids are also thought to help neutrophils survive longer.

This means the count can go up without the bone marrow being diseased and without an infection. It is one reason a single high result on steroids is read in context rather than on its own. The sources used here do not give a general figure for how much the count rises, so no number is given in this guide.

The guide on high neutrophils with low lymphocytes covers that wider pattern, which can be seen with infection, stress and steroids.

There is no single test that settles it. Clinicians usually combine several pieces of information:

• Symptoms and examination: signs such as fever, chills, sore throat or cough, which MedlinePlus lists as signs of infection to report while on prednisone.
• Timing: when the steroid was started, increased or given as an injection, compared with when the blood was taken.
• The differential: MedlinePlus explains that a blood differential measures each type of white blood cell. This shows whether neutrophils, lymphocytes or other cells are driving the high total.
• Immature cells: the American Academy of Family Physicians describes infection as often causing the release of younger neutrophils, called band cells, which is known as a left shift. A blood film (smear) can look for these and other changes.
• Trend and other tests: repeat counts, inflammation markers, cultures or imaging may be used if infection is suspected.

MedlinePlus lists infection, inflammatory diseases such as rheumatoid arthritis, allergy, tissue damage from burns or surgery, and less commonly leukaemia or Hodgkin disease. It adds that smoking, stress, a reaction to a medicine or pregnancy can also raise the count.

Cleveland Clinic says infection and inflammation are the most common causes, and that blood cancers and bone marrow disorders are less common. Because steroids are often prescribed for inflammatory conditions, the illness itself may be part of the picture. The general guide on high white blood cell count covers these causes in more detail.

Labs use different reference ranges. Cleveland Clinic describes a count above 11,000 white cells per microlitre as typically counted as leukocytosis, but always compare your result with the range printed on your own report.

No, not without medical advice. The NHS says do not stop taking a steroid without talking to your doctor first, and that stopping some steroids suddenly can cause symptoms such as extreme tiredness, feeling sick, dizziness and joint pain. MedlinePlus gives the same advice for prednisone and explains that stopping suddenly may leave the body without enough of its own natural steroids.

Do not change the dose or timing yourself, either. If a high count worries you, contact the prescriber. They can weigh the blood result against the reason you are taking the steroid.

MedlinePlus says the doctor will order lab tests to check the body's response to prednisone. A complete blood count with a differential is a common part of this. If the count is high, the team may repeat it, look at the trend over time, or arrange a blood film.

Cleveland Clinic notes that a bone marrow test is sometimes needed to confirm a diagnosis, but this is not routine for a raised count that fits with steroid treatment. Ask what result or symptom would change the plan.

Bring your blood reports with dates, a list of every steroid you have had (tablets, injections, inhalers or creams) and notes on any symptoms.

• Which white cells are raised, and does the pattern fit with my steroid?
• Was there any sign of infection or immature cells on the differential or blood film?
• Could the condition I am being treated for also be raising my count?
• Do you plan to repeat the count, and when?
• Which symptoms of infection should make me call you straight away?
• Should I keep taking my steroid exactly as prescribed for now?

On SameCase, patients and verified doctors share de-identified cases. Seeing how others with a raised count on steroids described their results, and which questions helped them, can make your own list more focused. Similar cases cannot tell you whether you have an infection or predict your results; your own care team makes those decisions.