Anemia (low red blood cells)
Red blood cells carry oxygen through your body. When they are low, you may feel tired, weak, cold, or short of breath.
Why it happens
Chemotherapy, radiation, and cancers that affect the bone marrow, like myeloma, leukemia, and lymphoma, can cause it. Bleeding, low iron, and kidney problems can add to it.
What helps
- Rest when you need to, and pace your activities.
- Get up slowly from sitting or lying down to avoid dizziness.
- Eat foods with iron and protein, like lean meat, beans, eggs, and leafy greens.
- Ask whether you need iron, vitamin B12, or folate testing.
- Keep track of how tired or short of breath you feel from day to day.
Call your care team right away if you have
- You feel short of breath at rest or your heart is racing.
- You have chest pain or feel like you might faint.
- You see blood in your stool, urine, or vomit.
Questions to ask
- What is my red blood cell count, and is it getting better or worse?
- Might I need a blood transfusion or other treatment?
- Could low iron or another vitamin be part of the cause?
Medicines that can cause this
- Edoxaban
- Enoxaparin
- Niraparib
- Olaparib
- Palbociclib
- Rucaparib
- Ruxolitinib
- Talazoparib
- Tarlatamab
- Tislelizumab
- Venetoclax
Sources
Quick answers
- What is anemia during cancer treatment?
- Red blood cells carry oxygen through your body. When they are low, you may feel tired, weak, cold, or short of breath.
- Why does anemia happen?
- Chemotherapy, radiation, and cancers that affect the bone marrow, like myeloma, leukemia, and lymphoma, can cause it. Bleeding, low iron, and kidney problems can add to it.
- What helps with anemia?
- Rest when you need to, and pace your activities; Get up slowly from sitting or lying down to avoid dizziness; Eat foods with iron and protein, like lean meat, beans, eggs, and leafy greens; Ask whether you need iron, vitamin B12, or folate testing; Keep track of how tired or short of breath you feel from day to day.
- When should I call my care team about anemia?
- You feel short of breath at rest or your heart is racing; You have chest pain or feel like you might faint; You see blood in your stool, urine, or vomit.
Last updated: 2026-10-27. Medically reviewed by Veli Bakalov, MD, medical oncologist (October 2026). General education from Step by Step, the patient portal of HemeOncBuddy.