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What are the side effects of antihistamines?

Antihistamines can cause various side effects that differ depending on the type used. Most people experience only minor side effects, but older antihistamines tend to cause more problems than newer ones. The most common side effects include drowsiness, headaches, dry mouth, and dizziness.

Key points:

• Older antihistamines cause more side effects, particularly drowsiness and reduced coordination, which can affect driving and work performance
• Newer antihistamines have fewer side effects overall, though headaches and dry mouth can still occur
• Digestive antihistamines (H2 blockers) used for stomach conditions may cause fatigue, diarrhoea, and muscle pain
• Long-term use of older antihistamines carries risks including memory problems, brain fog, and increased dementia risk

This text has been fact-checked for accuracy by medino's clinical team.