Hello dear ...
Thanks for your query.
First of all I would like to say that Deriphyllin[Theophylline] is neither used for infection or allergy.It is used for bronchial asthma
& COPD as a bronchodilator
.It was given to you to relieve symptoms of bronchospasm
.Are you having difficulty in respiration now ?Theophylline has got a narrow margin of safety and multiple sideeffects like gastric pain,dyspepsia,headache,tremors, nausea, palpitation etc. Dont self medicate. Get a check up from a doctor.
If you are having throat infection
,watering nose,fever you can use Levotrizine 5 mg tablet twice daily for 5 days. Tablet Paracetamol
500 mg twice daily for 3 days and thereafter sos . Tablet CoAmoxyclav 625 mg thrice daily for 5 days . Tablet Vit C 500 mg twice daily for a week.Do warm saline gurgle 4 times daily for 5 days.
But I dont think you will get medicine without doctor's prescription in USA.
Update here how you stay.
Take care :)