Inhalation is one of the methods to dispense medicine to the affected parts. This is used when the affected parts are the upper respiratory system . While the oral medicines take time to get into the blood stream and start their action, the medicines inhaled directly reach the nose, throat and lungs and start working immediately.
This has enabled the use of nebulisers and sprays and atomisers.
For the normal seasonal cold and related nose blocking the common inhalers( like Vicks, Amrutanjan or Emami) are helpful, in severe conditions one may need the nasal sprays with chemicals and even steroids.
The above named common cold inhalers contain aromatic essential oils of eucalypus, pepper, and other easily volatile essential oils. The inhaled vapour of the oils make their way through the blocked mucous and thus clear for air passage. They then reach the throat and lungs when taken in sufficient quantum and work better as they have medicinal effects in cold and minor infection conditions.
The chemical sprays and nasal drops on the other hand work differently. When they touch the surface of the inside nose and lugs, the body reacts by shrinking the blood vessels of the area and thus making way for air passage. Hence such chemical inhalers and sprays should be taken only under medical supervision and a qualified and experienced doctor's advice. Long-term use can become ineffective and may need increase of dose and potency of the drug and thus may cause harmful effects .
Even the normal aromatic oil based vaporisers and inhalers can cause minor bleeding and swelling of the external nose tips for persons who are sensitive and have not much exposure to such oils. So they should use them gradually and in small frequencies first.
Inhalers give effect for some very short time and may need repetition.
The most harmless method is steam inhalation or inhaling hot water vapours.
Here one should be very careful, because steam can cause burn if carelessly inhaled and exposed to sensitive skin and eyes. Nowadays there are steam inhalation apparatus , It is always better to take a test dose first and then adapt posture and quantum for exposure of inhalation.