Yes, dogs can take Benadryl (diphenhydramine) safely when given the proper dosage and under the guidance of a veterinarian. It is commonly used to treat allergies, itching, insect bites, food allergies, and even anxiety or motion sickness in dogs. The typical dosage is about 1 mg of Benadryl per pound of the dog's body weight, given 2 to 3 times a day. However, it is important to avoid Benadryl in dogs with certain conditions such as cardiovascular or lung diseases, glaucoma, high blood pressure, pregnancy, hypothyroidism, or seizure disorders. Also, only give formulations without additional ingredients like decongestants or alcohol, which can be toxic to dogs. Side effects are generally mild but can include drowsiness, dry mouth, or difficulty urinating, and overdoses can cause more severe symptoms like agitation or vomiting. Always consult a veterinarian before administering Benadryl to a dog to ensure safety and appropriate dosing.