On Shabbat, one may perform therapeutic treatments that are not normally done with the aid of medications. Since there is no concern that one will come to grind ingredients, such treatment is not included in the prohibition of medicine on Shabbat. However, if there is no real need, even such treatment is prohibited because it is a weekday activity. But as long as a real need exists, for example when one is in pain, it is permissible (SA 328:43; MB ad loc. 136).
Therefore, one may apply pressure to an injury with a utensil or his hand to prevent swelling, as this is a type of therapeutic action that is not normally done with medications (Ĥayei Adam 69:5; MB 328:144; SHT ad loc. 104). Similarly, one may apply ice to an injury in order to prevent swelling and reduce the pain, because this is not normally done with medicine (SSK 35:35 and n. 92).
If one’s eyes hurt, he may do eye exercises on Shabbat, because there is no medication that substitutes for these exercises. If one’s eyes do not hurt, but he wants to strengthen his eye muscles, the exercises have the same status as physical therapy exercises: if one needs to do them several times daily, one may do them on Shabbat as well (as explained in the next section).
One may place an orthodontic retainer in one’s mouth on Shabbat, as no medication can straighten one’s teeth (SSK 34:29).
One who has a stomach ache or an earache may place a hot water bottle on the affected area to relieve his pain (MB 326:19). Ice may also be used to relieve pain (SSK 33:15).
One who has an earache may put cotton in his ears. This is not considered medicinal, since it does not heal the ear, but simply protects it from the wind (SA 303:15; SSK 34:9). One who wishes to soothe his throat may swallow a raw egg, as this is not considered a medicinal act (SA 328:38). One may put talcum powder into one’s shoes to absorb sweat and foot odor or to soothe his feet. However, one who has athlete’s foot may not put medicated powder in his shoes. If he is in pain, though, he may (section 5 above).
. Shabbat 40b states that one may not place a container of hot water on a person’s stomach, due to the risk of spilling. Rashi and Ran explain that this is the reason for the prohibition on Shabbat as well, but Tosafot state that it is forbidden on Shabbat because of the ban on medicine on Shabbat. It would seem that according to Rashi and Ran, if the hot water bottle is sealed well, one may use it on Shabbat, whereas according to Tosafot it is still prohibited. MB 326:19 states that one may be lenient if there is a great need. Based on what we said in section 5, nowadays, when medicine is mass-produced, one may be lenient concerning all medicine for one in pain.