HydroBlog March 23, 2020

Combating COVID-19: Practical Suggestions

Moist Hot Pack/Fomentation

The moist hot pack or fomentation is a moist heating technique which holds its heat for a longer time, as opposed to dry heat, and different than the hot compress which is usually just a cloth dipped in hot water and wrung out.  Because the hot compress is smaller and doesn't hold it's heat as long it is usually used for more superficial skin conditions.  In contrast, the most hot pack/fomentation (sometimes also called “steam pack”) provides most, steaming heat to a larger area for a longer period of time, which will result in warmth and can produce relaxation in the muscles and deeper tissues of a localized area.

While dry heat modalities may maintain skin contact for longer periods of time, even up to several hours (such as dry heat wraps, etc.), moist heat packs are typically used for about 15-20 minutes or so. (4)  The prolonged application of a dry heat pack has advantages for certain conditions, but moist heat packs produce more of a skin-reddening effect which can relieve internal blood congestion from inflammation (8). Moist heat aids in the heat’s ability to penetrate into the muscles, and therefore may provide better pain relief in some instances (2), and also has the beneficial effect of increasing blood circulation in the skin (5).

The moist hot pack technique works best to relieve pain and increase flexibility when it is combined with other modalities such as physical therapy and exercise. Using hot packs is appealing to many people due to the fact that it’s non-invasive and non-pharmaceutical intervention. (2)


  • Musculoskeletal pain relief (2)
  • Comfort and relaxation (2)
  • Benefits for many types of lower back pain (2)
  • Increases the flexibility of soft tissue (6)
  • Dilates the blood vessels of the muscles which increases the flow of oxygen and nutrients to them helping to heal damaged tissue (2).Stimulates the sensory receptors in the skin, which will have the effect of decreasing transmission of pain signals to the brain (2).Helps to allow stretching of the soft tissues including muscles, connective tissue and adhesions, which results in decreased stiffness, increased flexibility and feelings of comfort (2).
  • Surprisingly has even been used successfully as a nonpharmacologic measure to prevent and relieve chest pain in acute coronary syndrome (recommended to check with health care provider first) (1).
  • May also benefit gas/bloating, bursistis, backache, arthritis, chest congestion/cough, asthma, etc. (8).
  • Laying a hot pack between the shoulder blades may help cough because of the derivative effect of the heat causing blood vessels of the sking to dilate and therefore reducing the internal blood congestion. It works even better if you do a hot foot bath at the same time, and can be beneficial to conditions pulmonary infection/inflammation for the same reasons (8).


The following conditions are contraindicated for using hot packs, because of the risk of burns or other serious complications.

Dermatitis (2)

Deep vein thrombosis (2)

Diabetes (2, 3) – especially not to feet

Peripheral vascular disease (2)

Open wound (2)

Do not put a hot pack over any area of numbness or decreased sensation

Recent injury (as a general rule, if the injured area is swollen or bruised it is better to apply ice or a cold pack to reduce the swelling, along with other first aid measures and seeing medical attention). (2)

Severe cognitive impairment. Those with decreased cognitive ability/confusion or inability to tell notify that they are in pain or getting a burn

Hypertension or heart disease (2) (recommended to consult a physician if prolonged or effecting large areas).

Some types of abdominal pain might represent appendicitis- so should not use heat for abdominal pain accompanied by fever, etc.

A large amount of subcutaneous fat could impair the transfer of heat from skin to deep muscle (4), which causes the skin temperature to increase more than for those with less subcutaneous fat.  This could potentially lead to burns.  In this case dry heat packs placed for a prolonged period of up to several hours (as directed per protocol) have a greater effect on deep muscles.


Bath towels and a pot of boiling water, or a dry heat source (such as hot water bottle), a wet wash cloth and some dry towels.


There are several different ways you can make moist heat packs. Physical therapy departments use moist hydrocollator packs separated from the skin by typically eight layers of towels (5).

At home, you can make a hot pack/fomentation with towels. 

Microwave method; get a towel wet and wring it out very well (no dripping, or it may burn you). Heat in microwave for 5-6 minutes for a large towel, 2-3 minutes for a small towel (or depending on your microwave).  Use a dry towel to grab the heated towel, to avoid burns, and wrap the hot towel with the dry towel, then put on your back. 

Boiling method; (usually requires two people in order to prevent burns).  With two people twist two ends of a towel in opposite directions until the towel starts to form a U shape.  Then dip the middle of the U into a pot of boiling water.  The two people then pull in opposite directions while twisting the towel to wring out all dripping water.  Next, place the steaming hot towel in the middle of another dry towel and fold the dry towel around it.  Place the hot pack onto the target area.  You may place a hot water bottle over the top of it to help it maintain heat longer.  Typically this method looses heat faster than other hot pack methods, because towels are usually made of cotton.  

Wool; cutting up a wool blanket to wrap around the hot towel will hold the heat longer.  You must still place 2-3 layers of a dry towel between the skin and the heat.

Wrapping a dry heat source with a moist cloth is another method.  For example, wrap a moist wash cloth over a hot water bottle or reusable commercial hot pack.  This has been determined to be a viable alternative to physical therapy hydrocollator steam packs (7). Be sure to protect the skin with dry towels as needed to prevent burns.

Moist hot packs should typically be wrapped in several layers of towels, and caution should be used to prevent the heat source from being hot to the point of burning the skin (2) Many times, a longer application of heat can result in better pain relief (2). 

The recommendation for moist heat is usually from 15-20 minutes.  For longer times or up to several hours it is better to use a dry heat source, such as heat wraps (4).  Electric heating pad can have negative side effects as well, including bone demineralization and effects from electromagnetic field. 

It's best to finish by rubbing the area with a cold compress (wash cloth dipped in ice water and wrung out), or a cold rinse of tap water, to close the pores, stop sweating and avoid chilling.




1.  Mohammadpour A, Mohammadian B, Basiri Moghadam M, Nematollahi MR. The effects of topical heat therapy on chest pain in patients with acute coronary syndrome: a randomised double-blind placebo-controlled clinical trial. J Clin Nurs.[Internet]. 2014 Apr 3 [cited 2014, Aug 25],[Epub ahead of print]. Available at;  http://www.ncbi.nlm.nih.gov/pubmed/24698126

2. Mooney, V. Benefits of Heat Therapy for Lower Back Pain[internet]. Spine Health [published 03/20/2003 cited 2014 August 25] Available from: http://www.spine-health.com/treatment/heat-therapy-cold-therapy/how-apply-heat-therapy


3. Mun JH, Jeon JH, Jung YJ, Jang KU, Yang HT, Lim HJ, Cho YS, Kim D, Hur J, Kim JH, Chun W, Seo CH. The factors associated with contact burns from therapeutic modalities. Ann Rehabil Med. [Internet]. 2012 Oct [cited 2014, Aug 25];36(5):688-95. Available at; http://www.ncbi.nlm.nih.gov/pubmed/23185734


4. Petrofsky J, Bains G, Prowse M, Gunda S, Berk L, Raju C, Ethiraju G, Vanarasa D, Madani P. Dry heat, moist heat and body fat: are heating modalities really effective in people who are overweight? J Med Eng Technol. [Internet]. 2009 [cited 2014, Aug 25];33(5):361-9. Available at; http://www.ncbi.nlm.nih.gov/pubmed/19499453

5. Petrofsky J, Bains G, Prowse M, Gunda S, Berk L, Raju C, Ethiraju G, Vanarasa D, Madani P. Does skin moisture influence the blood flow response to local heat? A re-evaluation of the Pennes model. J Med Eng Technol. [Internet]. 2009[cited 2014, Aug 25];33(7):532-7. Available at; http://www.ncbi.nlm.nih.gov/pubmed/19484652

6. Petrofsky JS, Laymon M, Lee H. Effect of heat and cold on tendon flexibility and force to flex the human knee. Med Sci Monit. [internet]. 2013 Aug 12 [cited 2014 Aug 25];19:661-7. Available at; http://www.ncbi.nlm.nih.gov/pubmed/23933600

7. Tomaszewski D, Dandorph MJ, Manning J. A Comparison of Skin Interface Temperature Response Between the ProHeat Instant Reusable Hot Pack and the Standard Hydrocollator Steam Pack. J Athl Train. [Internet]. 1992[cited 2014, Aug 25];27(4):355-9. Available at; http://www.ncbi.nlm.nih.gov/pubmed/16558193


8. Thrash, A, Thrash, C. Home Remedies. Seale: NewLifestyle Books; 2005.