The research question for the current study is: Is loratadine more effective than placebo in preventing G-CSF-related bone pain during autologous hematopoetic stem cell transplant in patients with lymphoma or multiple myeloma? The hypothesis is that prophylaxis with loratadine will help prevent or reduce the severity of bone pain in this setting.

Inclusion Criteria:

1. A histologically or cytologically documented lymphoma or multiple myeloma
2. Next line of therapy is autologous stem cell transplant
3. Adult ≥ 18 years old.
4. Eastern Cooperative Oncology Group (ECOG) Performance Status 0-2.
5. Life expectancy of at least 12 weeks.
6. The absence of any additional poorly controlled systemic disease that is directly contraindicated or places subject at significant risk, including but not limited to: congestive heart failure, diabetes mellitus, cirrhosis or liver failure, renal failure.
7. Able to adhere to study protocols and visit schedules

Exclusion Criteria:

1. Hypersensitivity or intolerance to antihistamines
2. Use of antihistamines within two days prior to the study period, excepting the use of single dose antihistamines during chemotherapy or blood transfusion protocols.
3. Recent use of G-CSF or pegfilgrastim defined as within 12 weeks of study accrual.
4. New and continued regular use of analgesics within the four days prior to the first dose of G-CSF