http://alcoholism.about.com/gi/dyna...ih.gov/medlineplus/druginfo/uspdi/202061.html
Other medicines—Although certain medicines should not be used together at all, in other cases different medicines may be used together even if an interaction might occur. In these cases, your doctor may want to change the dose, or other precautions may be necessary. When you are taking antihistamines it is especially important that your health care professional know if you are taking any of the following:
Alcohol—Effects such as drowsiness may be worsened.
Anticholinergics (medicine for abdominal or stomach spasms or cramps)—Side effects, such as dryness of mouth, of antihistamines or anticholinergics may be more likely to occur
Central nervous system (CNS) depressants—Effects, such as drowsiness, of CNS depressants or antihistamines may be worsened
Digitalis glycosides (e.g., Digoxin)—Use of this medicine may affect heartbeats.
Maprotiline (e.g., Ludiomil) or
Tricyclic antidepressants (amitriptyline [e.g., Elavil], amoxapine [e.g., Asendin], clomipramine [e.g., Anafranil], desipramine [e.g., Pertofrane], doxepin [e.g., Sinequan], imipramine [e.g., Tofranil], nortriptyline [e.g., Aventyl], protriptyline [e.g., Vivactil], trimipramine [e.g., Surmontil])—Effects, such as drowsiness, of CNS depressants or antihistamines may be worsened; also, taking these medicines together may cause some of their side effects, such as dryness of mouth, to become more severe
Monoamine oxidase (MAO) inhibitor activity ( isocarboxazid [e.g., Marplan], phenelzine [e.g., Nardil], procarbazine [e.g., Matulane], selegiline [e.g., Eldepryl], tranylcypromine [e.g., Parnate])—If you are now taking, or have taken within the past 2 weeks, any of the MAO inhibitors, the side effects of the antihistamines may become more severe; these medicines should not be used together
Rauwolfia alkaloids (alseroxylon [e.g., Rauwiloid], deserpidine [e.g., Harmonyl], rauwolfia serpentina [e.g., Raudixin], reserpine [e.g., Serpasil])—These medicines may increase or decrease the effect of the decongestant