**Diphenhydramine Hydrochloride BP** (British Pharmacopoeia standard) is an **antihistamine** with **multiple uses** due to its **anticholinergic, sedative, and antiemetic properties**. Here are its main uses:
# 1. **Allergy Relief**
- Treats symptoms of **seasonal allergies**, **hay fever**, and **allergic rhinitis**
- Reduces **sneezing**, **runny nose**, **itchy eyes**, **hives**, and **skin rashes**
# 2. **Cold and Flu Symptoms**
- Included in many **OTC cold and flu preparations**
- Helps relieve **cough**, **sneezing**, and **runny nose**
# 3. **Insomnia**
- Used as a **short-term sleep aid** due to its sedative effects
# 4. **Motion Sickness and Nausea**
- Prevents and treats **nausea**, **vomiting**, and **dizziness** associated with **motion sickness**