Hi, welcome to the forum, it typically suggests allergic rhinitis which is exaggerated or precipitated due to ketchup as a form of food allergy. One can be allergic to particular food types. The other common existing food allergens are Peanut flour, peanut butter, powdered egg white, Powdered/fresh milk Soy milk, soy flour Wheat breads, flour etc.
A careful nasal examination, Allergen-specific testing includes Skin testing, Serum tests for allergy, Allergen challenge and as well as Evaluation for concurrent conditions like Sinusitis and Asthma is necessary and it directs further steps for management.
You need to avoid intake of ketchup. Nasal decongestant will help to relieve nasal symptoms. If not controlled, corticosteroids nasal spray can be used. I suggest you to consult ENT specialist. Take care and regards.
you're congestion may be caused by a sensitivity to one or several of the ingredients in ketchup. many people associate sinus problems with just seasonal and other environmental allergies, but they can also be a reaction to the food you're eating. the best way to find out is to go to an allergist. otherwise, you could try taking a benadryl when you eat ketchup and see if that helps.