Potential Problems

• Common side effects of antihistamines are mild drowsiness; dryness of the nose, mouth, or eyes; upset stomach and headaches.
  
  

Considerations

• Alcohol consumption should generally be avoided when taking antihistamines. Alcohol increases side effects, especially drowsiness. It is also inadvisable to operate heavy machinery or drive when taking antihistamines.
  
  

Drug Combinations

• Antihistamines are often mixed with other drugs used to ease symptoms of cold, allergy and the flu. This includes pain relievers and fever reducers, such as acetaminophen, aspirin, and ibuprofen and cough suppressants, such as dextromethorphan. Doctors and pharmacists generally recommend reading the labels of these formulas for additional side effects.
  
  

Interactions

• Antihistamines may interact with other medications, and it is advisable that a doctor or pharmacist is consulted for those who use sleeping pills or sedatives, medicine for high blood pressure or muscle relaxants.
  
  

Warning

• Serious side effects that may require immediate medical attentions include fast or irregular heartbeat, rash, fever, seizures, difficulty swallowing, or swelling of the eyes, face, tongue, or lips. This may indicate a severe allergic reaction to the medication.