Common Phenergan Side Effects and Management Tips
Most Common Side Effects
The sedating antihistamine promethazine commonly causes drowsiness, which may persist into the following day. This occurs because Phenergan crosses the blood-brain barrier and blocks histamine receptors in the central nervous system. Other frequent effects include dizziness, dry mouth, blurred vision, and constipation due to its anticholinergic properties.
Managing Mild Side Effects
For drowsiness, avoid driving or operating machinery until effects wear off. Taking Phenergan at bedtime can minimise daytime sedation when treating allergies. Dry mouth responds well to sugar-free gum or frequent sips of water. Constipation may improve with increased fluid intake and dietary fibre. These effects typically reduce as your body adjusts to treatment.
Serious Side Effects Requiring Attention
Contact your GP immediately if you experience severe dizziness, confusion, irregular heartbeat, or difficulty breathing. Extrapyramidal effects like muscle stiffness or involuntary movements, though rare, need urgent medical assessment. Children may experience paradoxical excitation or restlessness instead of sedation.
Special Considerations for Different Forms
EverydayMeds supplies both Phenergan 25mg tablets and Phenergan elixir 5mg/5ml oral solution. The liquid form allows more precise dosing, particularly beneficial for elderly patients who may be more sensitive to side effects. Both formulations contain the same active ingredient and carry similar side effect profiles, though liquid absorption may be slightly faster.
When to Seek Medical Advice
Persistent side effects lasting beyond a few days warrant discussion with your pharmacist or GP. Signs of allergic reaction to Phenergan itself, including skin rash, swelling, or breathing difficulties, require immediate emergency treatment. Long-term use may increase the risk of movement disorders, so regular medication reviews are important.
