When considering a product for a blocked nose caused by allergy and asthma, it's important to know what the product is and its ingredients. Some nasal sprays or decongestants might help relieve nasal congestion, but certain medications can sometimes worsen asthma symptoms or interact with allergy treatments. It's best to consult your healthcare provider or pharmacist before using any new product to ensure it's safe and appropriate for your specific condition. Meanwhile, using saline nasal sprays or rinses can be a gentle way to relieve nasal blockage without affecting asthma. If your symptoms persist or worsen, please seek medical advice promptly.