There are 250 homeopathic remedies specifically listed in the homeopathic literature for seasonal allergies / hay fever. Although there are in fact thousands of remedies that could be used to treat someone who has allergy symptoms. A homeopathic remedy is chosen according to the symptoms that the sufferer is presenting. Each person who has hay fever has their own individual, unique set of symptoms. For example, a hypothetical "Fred" is allergic to ragweed, he suffers terribly with itchy eyes that tear up and burn, his nose runs (but the nasal discharge doesn't burn.) Even his breathing is affected and he can start wheezing and coughing. Fred feels better out in cold air and worse in a warm room. Fred should try homeopathic Ambrosia. Meanwhile, hypothetical "Harry" has itchy, red eyes and even the roof of his mouth and inside his nostrils are itchy. He has a runny nose and has lost his sense of smell and is sneezing a lot. Harry feels worse in the evenings. He might do well to try homeopathic Arundo. Choosing an effective homeopathic remedy requires observing closely what are the exact symptoms as well as what makes the person feel better or worse. You can get a homeopathic book and self-prescribe. Here are two that I like very much:Miranda Castro's The Complete Homeopathy Handbook
http://www.mirandacastro.com/shop/index.php?main_page=product_info&products_id=6
Laura Josephson's A Homeopathic Handbook of Natural Remedies
https://www.amazon.ca/Homeopathic-Handbook-Natural-Remedies-Effective/dp/0812991885?ie=UTF8&*Version*=1&*entries*=0
If you have no success self-prescribing then you can always consult with a professional homeopath to get a constitutional remedy. Constitutional remedies are chosen not just for your acute hay fever symptoms but are based on your entire self - physical, mental and emotional. A constitutional remedy helps to boost your immune system and to help you rebalance holistically.
