Decongestants are medicines that reduce the swelling of sinus openings. If you can unblock the obstruction, the pressure is relieved and mucous can drain. They are two type of decongestants available: nasal sprays and pills. Neither requires a prescription. They can be used singly or together.
Of nasal sprays on the market, oxymetalazoline (brand name: Afrin) works the fastest, and is generally well tolerated. It helps reduce nasal congestion in over 90% of people. The spray works in seconds and lasts for many hours, however it should not be used for longer than 3 days because the nose can become "addicted" to it--- rebound nasal swelling can occur with longer use. as long as you limit use to 3 days or less, it is safe and very effective.
If you are a new to using a nasal spray, practice squirting the container once or twice in the air just to learn how to use the canister to create a geiser-like squirt. When you have achieved this, spray once in each nostril. Remain relaxed when you spray: you don't need to inhale during the spray, cover the other nostril, or change your head position. Wait 5 minutes. Now administer a second spray to each nostril. Then, wait another 5 minutes and administer the 3rd spray to each nostril. This method will open up the lower nose allowing the subsequent sprays to reach higher in the nose where the sinus openings reside. You may do 3 sprays in each nostril in the morning and at night for 3 days and then STOP and put the Afrin away. One bottle should make it thru 4 years of college and perhaps graduate school.
Pseudoephedrine (Sudafed, Sudagest) is the most effective decongestant available in pill form. Pseudoephredrine will usually not make you tired, in fact, it has stimulant qualities. Some people are kept awake by pseudoephedrine if it is taken too close to bedtime. Sudafed comes in a short and long-acting versions. It may be taken with Afrin or used alone as a decongestant. Be aware that it is an ingredient in Claritin D, Mucinex D and Zyrtec D, and you wouldn't want to take additional pseudoephedrine while on those medicines. As with any medication, read the manufacturers directions to make sure it is appropriate with any other medicines being taken or conditions you have. Pseudoephedrine is fine to take until you feel your congestion and post- nasal drip has resolved.
Previously pseudoephedrine was available over-the-counter and was a key ingredient in most cold medicines like Dayquil, Tylenol Sinus, Dimetapp, etc. but this is no longer the case. As of 2006, it is only available by requesting it at a pharmacy, where it is stored behind the counter. Pseudoephedrine can be used to form methamphetamine--"crystal meth". To prevent criminal production of this drug, the government monitors purchases of pseudoephedrine and pharmacists are required to document all purchases. An over-the-counter substitute is currently sold as Sudafed PE, which is not quite as effective as pseudoephedrine.