We sometimes use loratadine (Claritin) to treat bone pain in patients receiving white blood cell growth factors. How does this work?

White blood cell growth factors are used in the prevention and treatment of febrile neutropenia in patients receiving myelosuppressive chemotherapy. They may also be used for mobilization of stem cells prior to autologous hematopoietic stem cell transplant, and in other indications to prevent adverse outcomes due to neutropenia.

Reported rates of bone pain with these medications are:

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  • filgrastim (Neupogen) and its biosimilar filgrastim-sndz (Zarxio), 11% to 30%;
  • pegfilgrastim (Neulasta), 25% to 45%; and
  • sargramostim (Leukine), 21%.1

The rates of bone pain vary between agents, and may be associated with higher doses such as those used for stem cell mobilization (eg, filgrastim 10 mcg/kg). Bone pain may also be more common in patients who are younger or are receiving taxanes (eg, paclitaxel [Taxol]).2

Bone pain from white blood cell growth factors involves multiple factors, including inflammation and histamine release. Although the exact mechanism of this pain is not well understood, one potential mechanism is that histamine may cause bone marrow edema and result in pain.

Treatment options for bone pain caused by white blood cell growth factors include antihistamines, nonsteroidal anti-inflammatory drugs (NSAIDs), acetaminophen, and opioids for severe pain. There is relatively limited clinical data studying the use of loratadine and other antihistamines for bone pain in this setting. There are some case reports on the use of loratadine, astemizole (no longer available in the United States), and hydroxyzine (Atarax) to manage bone pain due to white blood cell growth factors. In the report on the use of loratadine, a patient with severe bone pain thought to be due to pegfilgrastim took loratadine 10 mg daily starting the day prior to chemotherapy through 5 days following chemotherapy. This patient experienced a resolution in her pain and was able to continue receiving pegfilgrastim with her chemotherapy.

Loratadine may be preferred over older antihistamines such as hydroxyzine, as it is associated with less sedation and fewer anticholinergic side effects (eg, dry mouth), although these may still occur in some patients. Patients receiving loratadine for bone pain due to white blood cell growth factors should be educated about potential adverse effects of loratadine, and counseled to report pain that is not well controlled.


1. Micromedex Healthcare Series. Greenwood Village, CO: Thomson Micromedex.

2. Romeo C, Li Q, Copeland L. Severe pegfilgrastim-induced bone pain completely alleviated with loratadine: a case report. J Oncol Pharm Pract. 2015,21(4):301-304.

2016 Drug Take-Back Day

The 11th National Prescription Drug Take-Back Day is scheduled for April 30, 2016. At these events patients can turn in prescription medications, including controlled substances such as opioids, for safe and secure disposal. These events are sponsored by the Drug Enforcement Agency (DEA) and thus far have collected more than 5.5 million tons of drugs. Not all sites may be able to take back chemotherapy, so patients are advised to go to www.deadiversion.usdoj.gov/drug_disposal/takeback/ for details, and to find a take-back site in their community.