If a person suffers from nasal congestion on Shabbat, is it permissible for him to smell Vics to clear his nasal passageways so that he can breathe easier, or does this fall under the prohibition against taking medications on Shabbat?
Halacha permits this kind of congestion relief on Shabbat, because it does not qualify as "medication" in the true sense of the term. Vics does not cure the cold; it simply has the effect of temporarily opening one’s nasal passageways, without actually providing a cure. The prohibition of "Refu’a" (medication) on Shabbat applies only to medicines, remedies that cure the patient’s condition, and smelling Vics is therefore permissible. Moreover, Vics is simply smelled, and not ingested, and for this reason, too, one may be lenient with regard to this kind of remedy on Shabbat.
Summary: It is permissible to relieve nasal congestion on Shabbat by smelling Vics.