The best way to relieve a stuffy nose is to do steam inhalations with essential oils, such as eucalyptus and thyme. Prepare the inhalation with three drops of each oil, three times a day. Drink lemon juice, which is rich in antioxidants and vitamin C.
Also, after meals, drink ginger herbal tea twice a day. Finally, on an empty stomach, take a tablespoon of honey with a small teaspoon of apple cider vinegar, and repeat this before sleeping.
You can also do hijama as for sinusitis; for this, see a qualified and certified practitioner.
What the science says: essential oils
What published research says about the remedies mentioned above, for context — the studies address material causes, and healing belongs to Allah.
Essential oils
Tea tree essential oil has documented effectiveness for acne (Antioxidants, 2023), peppermint oil for irritable bowel syndrome (Aliment Pharmacol Ther, 2022), and lavender and others for anxiety (Pharmacol Res, 2022) — but these are powerful concentrates. Precaution: always dilute before applying to the skin, never use in the eyes or undiluted by mouth without medical advice; several of these oils are prohibited for pregnant women (except on medical advice), children under 3 (under 6 for peppermint), asthmatics, and people with epilepsy.