Which Is Harder on the Body: Chemo or Radiation?

Learn more about each treatment, their differences, side effects, and more

When undergoing cancer treatment, you may wonder about the pros and cons of different treatment approaches. Which treatments have fewer side effects and would let you keep living your life while undergoing treatment?

You may hear your doctor suggesting chemotherapy (which is often associated with specific side effects like hair loss and nausea) or other treatment options, including radiation. Which of these are harder on the body?

Both chemotherapy and radiation are important treatment approaches to improve survival in cancer patients, but they act on the body (and cancer) in different ways. You may wonder if being prescribed a treatment regimen that includes chemotherapy is harder on the body than if you’re given radiation treatments. 

This article will cover chemotherapy and radiation as cancer treatments, their differences, side effects, and more.

Chemotherapy vs. Radiation

Verywell / Jessica Olah

What Is Chemotherapy?

One of the oldest treatments for cancer is chemotherapy, in which drugs are given through an intravenous (IV) injection or orally. Chemotherapy can have effects system-wide, which means it impacts your whole body.

The goal of chemotherapy is to kill the cancer cells, shrink the tumor, or destroy the tumor. Destroying the tumor can eliminate cancer, while shrinking it can relieve some symptoms if the tumor is causing pain or interfering with other tissues.

These drugs specifically damage and kill cells that grow quickly. They interfere with the cells' ability to divide. Cancer cells grow uncontrollably and often much quicker than other tissues and cells in the body, so these compounds damage them. 

But some specific parts of the body have a fast turnover of new cells and are also impacted by chemotherapy medications, leading to side effects in parts of the body that are unaffected by cancer.  

What Is Radiation?

Radiation is a high-energy invisible light wave. Because it has a lot of energy, it can be directed at cancer cells to damage their genetic material, ultimately killing them.

The radiation waves damage the cancer cells, which die over time and are removed by the body, causing the tumor to shrink. This process can continue for weeks or even months after treatment is over.

Radiation is used in many ways as a cancer treatment. The goal of radiation is usually to slow the growth of, shrink, or destroy a cancerous tumor. 

The radiation is applied in one of two ways. Internal radiation is an injection of radiation in a solid or liquid into the tumor or nearby tissues. External beam radiation is the application of radiation from a beam generated by a machine outside the body. 

External beam radiation and solid internal radiation injections are local treatments—meaning the radiation is applied only at the site of a primary or secondary tumor, not throughout the whole body. 

On the other hand, internal liquid radiation treatments act systemically—the radiation travels throughout your body. As a result, these treatments can damage cancer cells that have spread away from visible tumors, reducing the likelihood that cancer will spread or come back after other local treatments like surgery.

The type of radiation used in your treatment plan depends on your cancer type, how large the tumor is, where it is located in the body, and your general health and treatment history.   

Benefits and Risks of Chemotherapy

Chemotherapy is an essential treatment option for many cancers. The drugs used in chemotherapy are often given so that they can reach and kill cancer cells system-wide, outside of the primary tumor your doctor may have discovered. 

When cancer spreads, it can be challenging to treat. So chemotherapy is an important treatment option to help kill cancer cells that may have escaped the primary tumor and spread to other parts of the body but are too small to see; these are called micrometastases.

Chemotherapy can also help treat any tumor pieces or cells left over after other treatment approaches, like surgery or radiation therapy. 

But because the drugs used in chemotherapy can be nonspecific to cancers and impact other healthy tissues of the body, they cause some side effects. These side effects are typically limited to when you’re actively being treated with chemotherapy and will rapidly improve after treatment is discontinued.

Common side effects of chemotherapy include: 

You’ll also likely feel exhausted by the treatments and need to take time off work (and other duties like childcare and meal prepping) the day of and the day after your treatments. 

Chemotherapy is often given in cycles. For example, you may receive one week of treatment and then have a few weeks off to allow your body to heal before the next treatment. 

Radiation’s Benefits and Risks

Radiation treatments can continue killing cancer cells for weeks or months after your initial treatment.

Different types of radiation treatment will have different risks and side effects. For example, local radiation can have side effects if nearby healthy tissues are damaged during treatment. 

Side effects of radiation may include nausea, mouth sores, and throat problems that make it hard to eat. You’ll also feel exhausted and weak as your body works to heal and remove damaged cells. 

Systemic radiation with an internal radioactive liquid can have more side effects throughout the body. Still, local radiation can have specific side effects depending on where in the body you are getting treated.

You'll likely feel pretty good when starting radiation treatment but feel progressively more run-down as your treatments continue, and even after they're done. Side effects from radiation should improve within a few weeks or months, but some may persist or show up in the longer term—months or even years after treatment.

Which Is Harder on the Body: Chemo or Radiation?

It is difficult to say what cancer therapy will be more difficult for your body to handle. Different types and dosages of both chemotherapy and radiation will have different effects. 

These effects also differ by the person getting them. So, for example, someone on one treatment might have extreme nausea, while another might have extreme tiredness. 

A systemic treatment like chemotherapy or liquid radiation may have more off-target side effects than a local treatment. But local treatments that are administered only to the cancer site, like external beam radiation or solid internal radiation treatment, may have more extreme side effects in that area of the body. 

Ask your doctor about what treatment options apply to you and how they could adjust these treatments or care for your symptoms if you have side effects.

Can Chemo and Radiation Be Used Together to Treat Cancer?

Some cancers can be treated with just radiation. These are most often cancers caught early—before they've grown large or started to spread.

Most of the time, cancer treatment plans will contain multiple treatments. These treatments can include radiation, chemotherapy, hormone therapy, surgery, targeted therapies, or immune therapies. When your doctor combines multiple treatments at once, it’s called a combination treatment plan.

Combination treatments are used for many reasons. Treatments may be more effective when they’re combined. For example, chemotherapy may make radiation treatments more effective.

If your doctor suggests undergoing one type of treatment before others, it’s called neoadjuvant treatment. Neoadjuvant treatments are typically used to shrink a tumor or destroy metastases before the primary tumor is surgically removed.

Treatments that come after others are called adjuvant treatments and are typically used to reduce the risk that cancers will return or spread after initial treatment or surgery on the primary tumor. 

Managing the Side Effects of Cancer Treatment

Many of the side effects of cancer treatment can be effectively managed or lessened. Palliative care (treatment to reduce the burden of symptoms) is an important part of any cancer treatment plan.

Suffering through debilitating or distressing side effects of your treatments doesn’t make your battle against cancer more heroic. Nor does it mean that your chemotherapy will work better.

Tell your doctor about the side effects you’re experiencing and get holistic help from your care team to ensure your treatment goes as smoothly as possible. Your doctor may be able to tweak your cycle schedule or dosage of radiation or chemotherapy to help improve your side effects. 

If you’re worried about taking time off work, make sure to talk to your employer. Many employers are legally required to give time off work or adjust your workload or schedule while you’re undergoing cancer treatment. A social worker on your care team can help you navigate this sometimes tricky situation.


Chemotherapy and radiation therapy are each used to treat cancer. The decision about which one is used depends on the type, location, and spread of the cancer. Chemotherapy is a systemic treatment, while radiation therapy is often a localized treatment but may be systemic.

Both can have side effects, which can differ by the patient and how the treatment is given. Whether one treatment is harder on the body than another will vary accordingly. Sometimes they are both used to treat a person's cancer.

A Word From Verywell

The treatment plan your doctor comes up with will be specific to your type of cancer, as well as its stage and other considerations, like your age and general health. These factors play an important role in what treatments will ultimately work best for you and leave you with the best possible chance for survival.

Some cancers have multiple treatment options, while some have few.  Large studies of cancer patients and treatments are used to determine the best treatment option for any given patient.

Your doctor uses published guidelines based on these studies to determine the best course of action for treating your cancer based on what is currently known. Your doctor knows your situation best, but feel free to get a second opinion from another doctor by giving them access to your records and information. 

Frequently Asked Questions

  • How long does it take to feel like yourself after chemo and radiation?

    Side effects from chemotherapy and radiation should start to improve as soon as your treatment stops. But it may take a few weeks or even months to feel better after radiation treatments.

    Side effects can even show up months or years after you’ve finished your cancer treatments. These are called late effects and are specific to the type and dose of cancer treatment you’ve received.

  • Is chemo or radiation used first to treat cancer?

    Your doctor's treatment approach for your cancer is individually crafted for you. For example, your treatment plan is determined by the type of cancer you have, how advanced it is, and other characteristics of your cancer and your health. 

    Your specific cancer treatment plan may include radiation, chemotherapy, or other treatments, including hormone therapy, surgery, targeted, or immune therapies. Your doctor may suggest any of these treatments in combination or succession. 

    The order in which therapies are given depends on their purpose. For example, chemo or radiation may be given before surgery to shrink a tumor to make it easier to remove. Or they may be given after surgery to ensure all cancer cells are removed from the body. 

  • Will chemo and radiation shorten your life span?

    A 2020 study used simulations to estimate the life expectancy of adult survivors of childhood acute lymphoblastic leukemia. They found that the treatments the patients received during childhood may have decreased their life expectancy by about 14% to 25%, depending on the decade in which they were treated for cancer.

    This study, though, was on treatments given during childhood to patients with a specific disease. These treatments have advanced through the decades, resulting in greater life expectancy for more recent patients. 

    This study can’t tell us how chemotherapy and radiation treatments may impact the life span of adult cancer patients.

8 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. National Cancer Institute. Chemotherapy to treat cancer.

  2. National Cancer Institute. Radiation therapy for cancer.

  3. National Cancer Institute. Definition of micrometastasis.

  4. National Cancer Institute. Radiation therapy side effects.

  5. National Cancer Institute. Combination treatments.

  6. American Cancer Society. Understanding your options and making treatment decisions.

  7. National Cancer Institute. Coping – late side effects.

  8. Yeh JM, Ward ZJ, Chaudhry A, et al. Life expectancy of adult survivors of childhood cancer over 3 decades. JAMA Oncol. 2020;6(3):350-357. doi:10.1001/jamaoncol.2019.5582

By Jennifer Welsh
Jennifer Welsh is a Connecticut-based science writer and editor with over ten years of experience under her belt. She’s previously worked and written for WIRED Science, The Scientist, Discover Magazine, LiveScience, and Business Insider.