While the overall qualities of warmth and heat have long been associated with comfort and relaxation, heat therapy goes a step further and provides both pain relief and healing benefits for many types of lower back pain.

In This Article:

8 Essential Ways Heat Therapy Alleviates and Heals Lower Back Pain

The most prominent benefits of heat therapy for back pain are achieved through the following ways:

1. Heat therapy speeds up the healing process

Heat therapy promotes healing by increasing blood flow to the muscles in the lower back. Increased blood flow delivers more oxygen, white blood cells, platelets, and essential nutrients – all of which help repair damaged tissues heal.

Sensory nerves respond to applied heat by releasing chemical messengers that dilate local blood vessels and enhance the speed of blood flow. 1 Petrofsky J, Berk L, Bains G, et al. Moist heat or dry heat for delayed onset muscle soreness. J Clin Med Res. 2013;5(6):416-425. doi:10.4021/jocmr1521w Both the applied heat and the increased blood flow help the skin temperature rise to match the body’s core temperature. After the skin reaches the core temperature, the blood absorbs excess heat and protects the skin from burns. 2 Petrofsky J, Paluso D, Anderson D, et al. The contribution of skin blood flow in warming the skin after the application of local heat; the duality of the Pennes heat equation. Med Eng Phys. 2011;33(3):325-329. doi:10.1016/j.medengphy.2010.10.018

Heat also transfers from the skin surface deep into the muscles, and improves blood circulation into the muscles. In this process, the heat has to cross the layer of fat right under the skin, which may be an obstacle to effective heat therapy in people who have a thicker fat layer. 3 Petrofsky J, Bains G, Prowse M, et al. Dry heat, moist heat and body fat: are heating modalities really effective in people who are overweight?. J Med Eng Technol. 2009;33(5):361-369. doi:10.1080/03091900802355508 , 4 Petrofsky JS, Laymon M. Heat transfer to deep tissue: the effect of body fat and heating modality. J Med Eng Technol. 2009;33(5):337-348. doi:10.1080/03091900802069547

2. Heat calms painful muscle spasms

Most forms of lower back pain involve some element of lower back muscle spasms. While it sounds minor, muscle spasms can be severely painful and in fact are a common cause of visits to the emergency room.

See Pulled Back Muscle Treatment

As a result of muscle spasms, circulation is restricted and pain signals are sent to the brain. Heat therapy can help relieve tightness in the lower back by recouping circulation, relaxing tense muscles, and reducing related pain.

See What Is Your Back Muscle Spasm Telling You?


3. Heat reduces pain caused by stiffness

Heat application facilitates stretching of the soft tissues around the spine, including muscles, connective tissue, and adhesions. Consequently, regular heat therapy on the back typically provides:

  • Decreased stiffness and injury
  • Increased range of motion 5 Bleakley CM, Costello JT. Do thermal agents affect range of movement and mechanical properties in soft tissues? A systematic review. Arch Phys Med Rehabil. 2013;94(1):149-163. doi:10.1016/j.apmr.2012.07.023
  • Strengthened movements of the trunk 6 Freiwald J, Hoppe MW, Beermann W, Krajewski J, Baumgart C. Effects of supplemental heat therapy in multimodal treated chronic low back pain patients on strength and flexibility. Clin Biomech (Bristol, Avon). 2018;57:107-113. doi:10.1016/j.clinbiomech.2018.06.008

An overall feeling of comfort sets in and daily activities seem less difficult when lower back stiffness is relieved.

4. Heat makes therapeutic exercises more tolerable

Physical therapy, stretching, and exercise are foundational components of most lower back pain treatment regimens. Heat therapy is typically applied to the lower back immediately before a physical therapy session and it is advisable to apply heat before exercising and stretching.

See Physical Therapy for Low Back Pain Relief

In addition, frequent heat therapy at home makes it possible to complete exercises more easily, 7 Petrofsky JS, Laymon M, Alshammari F, Khowailed IA, Lee H. Use of low level of continuous heat and Ibuprofen as an adjunct to physical therapy improves pain relief, range of motion and the compliance for home exercise in patients with nonspecific neck pain: A randomized controlled trial. J Back Musculoskelet Rehabil. 2017;30(4):889-896. doi:10.3233/BMR-160577 in between and long after physical therapy sessions. By facilitating consistent exercises, heat application is bound to improve the overall outcome of physical therapy for neck or back pain.

5. Heat interrupts the transmission of pain signals

The gate-control theory of pain involves sensory receptors that are located at nerve endings. Receptors compete with one another to reach the brain, and it is possible that one set of activated receptors mutes or blocks another set of receptors. Heat therapy activates heat-sensitive calcium channels that can block pain receptors directly or stimulate other sensory receptors to reduce pain indirectly. 1 Petrofsky J, Berk L, Bains G, et al. Moist heat or dry heat for delayed onset muscle soreness. J Clin Med Res. 2013;5(6):416-425. doi:10.4021/jocmr1521w

6. Heat produces relaxation chemicals

Heat therapy can reduce mental stress, as indicated by cortisol levels in the blood 8 Antonelli M, Donelli D. Effects of balneotherapy and spa therapy on levels of cortisol as a stress biomarker: a systematic review. Int J Biometeorol. 2018;62(6):913-924. doi:10.1007/s00484-018-1504-8 , and also reduce oxidative stress on a chemical level. The relaxing effect of heat is why so many spa treatments feature the use of heat application, such as hot stones, hot towels, and hot baths.

7. Heat boosts immunity

Elevated body temperature from heat therapy (external heat) mimics the function of a fever (internal heat), which is to stimulate the immune system to respond at multiple levels.

Research suggests that regular use of certain heat therapies provides:

  • An activated immune system. Hot baths activate monocytes, a type of white blood cell that helps remove dead cells, fight infections, and release more cytokines, 9 Ramirez FE, Sanchez A, Pirskanen AT. Hydrothermotherapy in prevention and treatment of mild to moderate cases of COVID-19. Med Hypotheses. 2021;146:110363. doi:10.1016/j.mehy.2020.110363 which are small proteins that act as signals between immune cells and other cells of the body.
  • A decrease in inflammatory markers. Frequent visits to a sauna are associated with lower levels of C-reactive protein in the blood. 10 Laukkanen JA, Laukkanen T. Sauna bathing and systemic inflammation. Eur J Epidemiol. 2018;33(3):351-353. doi:10.1007/s10654-017-0335-y Low levels of this protein indicate a strong immune system. Regular balneotherapy (hot baths using mineral water) lowers the levels of interleukin-1 and leukotriene B4, 11 Ardiç F, Ozgen M, Aybek H, Rota S, Cubukçu D, Gökgöz A. Effects of balneotherapy on serum IL-1, PGE2 and LTB4 levels in fibromyalgia patients. Rheumatol Int. 2007;27(5):441-446. doi:10.1007/s00296-006-0237-x Lloyd A, Scott DA, Akehurst RL, Lurie-Luke E, Jessen G. Cost-effectiveness of low-level heat wrap therapy for low back pain. Value Health. 2004;7(4):413-422. doi:10.1111/j.1524-4733.2004.74004.x both of which are proteins involved in inflammation.

The long-term effect of heat therapy includes a reduction of low-grade inflammation that is often seen in chronic pain conditions. The short-term effect of heat application on damaged, infected, or swollen tissues is an increase in inflammation. For this reason, localized heat therapy is avoided immediately after injury (typically avoid heat for the first 48 hours and apply cold compresses to help with acute inflammation).

See Ice Packs for Back Pain Relief


8. Heat reduces reliance on medications

Heat therapy is more effective and more cost-friendly than over-the-counter pain medications. 12 Lloyd A, Scott DA, Akehurst RL, Lurie-Luke E, Jessen G. Cost-effectiveness of low-level heat wrap therapy for low back pain. Value Health. 2004;7(4):413-422. doi:10.1111/j.1524-4733.2004.74004.x The low risk of side-effects is one of the key advantages of heat therapy. Low back pain tends to arise frequently, so treatment with pain medications for every episode of pain may lead to drug dependence. Heat therapy offers a valuable alternative to drug therapy for chronic low back pain.

See Medications for Back Pain and Neck Pain

Heat application is the treatment of choice for individuals who desire a natural form of pain relief that simultaneously acts on multiple levels – healing the body, soothing the muscles, facilitating exercise, and relieving stress.

Dr. Scott Curtis is a sports medicine specialist at Princeton Spine and Joint Center, where he serves as the center’s Director of Sports Medicine, specializing in sports-related injuries and general musculoskeletal care.