If Vidalista 5 mg contains tadalafil, an allergic reaction is uncommon but can be serious. Signs include: Skin rash or hives Itching Swelling of the lips, face, tongue, or throat Difficulty breathing or swallowing D DailyMed +1 Seek emergency help immediately If you develop swelling of the throat/tongue or difficulty breathing, stop taking the medicine and seek emergency medical attention. Severe hypersensitivity reactions, including serious skin reactions, have also been reported with tadalafil. D DailyMed Headache, flushing, indigestion, or mild dizziness are common tadalafil side effects and don't necessarily mean an allergy. If you tell me what symptoms you experienced after taking Vidalista 5 mg and how long afterward they started, I can help you distinguish a possible allergy from a normal side effect.