Allergies do NOT usually cause swollen lymph nodes
, but infections. You are either prone for recurrent sore throat
etc that causes the lymph nodes to swell up.
Rhinosinusitis (bacterial) can be very troublesome and difficult to treat, and a CT scan is the best modality of investigation in this setting.
Penicillin can decrease lymph node swelling in infections, but not recommended for sinusitis or for hair loss.
If recurrent lymph node enlargement and hair loss is a feature, suggest you get the following tests done and seen by a physician or Rheumatologist
if any of them are abnormal: CBC, fasting glucose and lipid profile
, LFTs, creatinine, ANA, TSH (thyroid profile).