I think it is probably better to suffer the symptoms than to discover in the field that you don't tolerate a medication. Other than antibiotics very few curative medications have been discussed here. Symptom relief is just that. Analgesics, decongestants, antacids etc help relieve symptoms but do nothing to remedy the underlyng illness. If you find the sinus soo debilitating that you need some relief from it then some sudafed might be helpful in your FAK. OTOH, if you have never taken sudafed then a survival situation is not the right time to discover that you are alergic to sudafed. The sinus headache is far superior to anaphalatic shock resulting in inability to breath, and death. The sinus headache is probably superior to the drowsiness that causes you to walk over the edge of a cliff or to make the decision to fall asleep rather than bother to build a proper shelter and fire. If there is a medication that you have experience with that you find helpful when you have a cold - by all means include some of it in your FAK. OTOH testing medications for the first time in the field is very dangerous.

IMNSHO, I would never include any medication that I knew caused drowsiness. In a survival situation I would want full alertness and I would want to be able to choose my sleep schedule. I do carry earplugs and eye shades so that if I have established safe shelter I can safely sleep even if it is loud and bright.