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Hot Packs how to use hot packs and its effects

Hot Packs is one of the sources to provide superficial heat. They are used for relieving muscle spasm, increasing the range of motion and pain relief.

Physiological and Therapeutic Effects:

  • It increases the local body temperature through the conduction of heat from hot packs to skin and superficial tissues (the increase of body temperature should be less than 45 degree centigrade otherwise burn can occur)
  • Increase in temperature cause vasodilatation. vasodilatation results in increse in blood supply especially in superficial tissues.
  • Pain relief following hot packs may occur due to decrease in nerve conduction velocity or elevated pain threshold.
  • Hot packs can relief muscle spasm by decreasing alpha motor neuron firing. as a result, reduced muscle spindle activity occurs.
  • It increases the soft tissues extensibility.
  • Can be used to break the adhesions.


  • Impaired skin sensation.
  • Circulatory dysfunctiion.
  • Analgesic drugs.
  • Infections and open wound.
  • Cancer and Tuberculosis.
  • Gross Edema.
  • Lack of comprehension.
  • Deep X-Ray therapy.
  • Liniment.
  • Recent hemorrhage.
  • Skin allergy.


  • Make sure that the patient should not lie on top of a hot packs, if the trunk is the area under treatment.
  • Do not apply hot packs on very overweight patients because tissues would not be able to dissipate the heat and this can cause a burn.

Types of hot packs:

  • Hydrocollator Packs.
  • Hot water bags.
  • Kenny packs.
  • Chemical hot packs.
  • Electrical heating packs.
Hydrocollator Packs:
  • These packs have silicate gel like bentonite in them. This gel is usually enclosed in a fabric container of cotton. Gel absorbs hot water in it and provides heat. It is available in different sizes in the market to fit different areas of the body properly.
  • There is a special tank having warm water in it. the water is warmed up to about 75-80 c in which these packs are placed. this water is made hot by an electric heater whose heat can be controlled by a thermostat.
  • Packs on racks are placed in hot water for about 2 hrs but when they are reheated, they can be placed for lesser time.
  • Then wrap the pack in towel in a way that 4-8 layer thickness should be present between skin and pack. Although the temperature of the pack is 75 c butt the temperature of skin does not increase above 42 c.
  • Now pack is loosing its temperature at the same time, loss of heat by skin is prevented by towel.
  • Packs should remain on the part for about 20-30 min to obtain the desired therapeutic effects.

hot packs

Hot Water Bags:
  • It is a rubber bag that is filled with one half full of water whose temperature is maintained at about (115 f-125 f)
  • Apply a towel over area to be treated and then place hot bag over that towel.
  • According to British standards, temperature should not be greater than 42 c.
  • Danger with these hot water bags is that these can break suddenly after being filled with hot water and can cause scald on the body of the patient where they are applied.
Kenny Packs:

These packs were widely used in the past for treating muscle soreness and tightness occuring in polio. In such packs, a lint piece or some woolen material is dipped in boiling water and then dry it and apply to skin at a temperature of about 60 c. After 5 min when the temperature of pack is almost equal to body temperature, replace that pack.

hot packs

Hot Packs:
  • A hot pack is the one which contains sodium acetate and water.
  • There is a seal on this pack, break the seal and shake the pack.
  • This shaking will dissolve the chemical in water.
  • Dissolution of chemical in water is an exothermic process and in this way, heat is released.
  • This Released heat is used for treatment purposes as in minimizing the swelling in the muscle and joint sprains.

hot packs

Electrical Blanket:

  • This is a kind of blanket which has an electrical heating device integrated in it.
  • It has a mattress pad that is placed under bottom bed sheet.
  • Like a heating pad, these have insulated wire that is being inserted in the fabrics.
  • Fabric gets heated when the wire is plugged in.
  • Temperature control unit between blanket and the electric outlet controls the current.
  • these blankets mostly work on low voltage like 12-24 volts.
  • These blankets can cause burns if they are older and if the patient is unable to sensitize heat like diabetics, children and elderly.

hot packs