It sounds like you are experiencing an allergic reaction, likely contact dermatitis from the hair treatment chemicals. Since you have already taken fexofenadine (Allegra), this should help reduce the itching. You can gently wash your scalp and hair with lukewarm water and a mild, fragrance-free shampoo to remove any remaining chemical residue. Applying a cool, damp compress or a mild, over-the-counter hydrocortisone cream to the affected skin can also provide relief. Please avoid scratching to prevent infection. If the rash continues to spread, or if you develop swelling in your face, lips, or have any difficulty breathing, please seek immediate medical attention.

Since your blood and urine tests are clear, we can rule out many common internal causes. Sometimes, chronic itching without a rash can be triggered by deep skin dryness, nerve sensitivity, environmental factors, or even stress. Since oral antihistamines only offer temporary relief, gentle skin care routines and topical treatments like moisturizers containing pramoxine can help soothe the nerve endings in your skin. I highly recommend discussing these possibilities with a dermatologist to help find you lasting comfort.

As the antihistamine provides relief, your symptoms could be due to contact dermatitis (an allergic reaction to something touching your skin) or chronic hives. For long-term management, identifying and avoiding personal triggers is key. A doctor may recommend a daily, non-drowsy antihistamine or mild topical corticosteroid creams for flare-ups. I highly recommend visiting a dermatologist or allergist for a personalized evaluation to find lasting relief.

The weakness and burning around the eyes could be related to the underlying viral illness itself, as fatigue and eye irritation are common with colds. Additionally, fexofenadine (Allegra) can sometimes cause mild dryness in the eyes, leading to a burning sensation, or slight drowsiness. While paracetamol is generally well-tolerated, the combination of illness and medication can sometimes make you feel run down. Please ensure you stay well-hydrated and rest. If these symptoms persist, worsen, or if you notice any swelling or vision changes, please consult your doctor for a personalized evaluation.

To manage your allergic runny nose and cough, first identify the trigger via an allergy skin prick test or a specific IgE blood test. For immediate relief, use daily antihistamines and steroid nasal sprays. Prevent recurrences by avoiding common triggers like dust mites, pollen, and pet dander. Wash bedding in hot water and use indoor HEPA air purifiers. For a permanent cure, consult an allergist about allergen immunotherapy (allergy shots or under-the-tongue drops). This treatment gradually trains your immune system to stop reacting to the specific allergen, providing long-term relief.

Yes, you can take either cetirizine or Allegra (fexofenadine) to help soothe the itching and reduce the redness. Both are antihistamines that can provide good relief. Please choose just one, as taking them together is not recommended. Make sure to follow the package instructions. If your rash spreads, does not improve after a few days, or if you start feeling unwell, please have a doctor examine it to ensure you get the right care.