Promethazine is known as a drowsy (sedating) antihistamine as it makes you sleepy. Non-drowsy antihistamines are less likely to have this effect. These include cetirizine, fexofenadine and loratadine. Most people prefer to take a non-drowsy antihistamine as it's less likely to interfere with their everyday routine. You might choose to take a drowsy antihistamine, however, if you're having problems falling asleep, or if symptoms like itching or coughing are keeping you awake. There is not enough information available to say whether one antihistamine is better than another for treating allergies. You may need to try a few different medicines to find what works best for you. Ask your pharmacist or doctor for advice if you're unsure.