Omnihist L.A. Side Effects
Generic name: chlorpheniramine / methscopolamine / phenylephrine
Note: This document contains side effect information about chlorpheniramine / methscopolamine / phenylephrine. Some of the dosage forms listed on this page may not apply to the brand name Omnihist L.A..
For the Consumer
Do not use this medicine if you have taken an MAO inhibitor in the past 14 days. A dangerous drug interaction could occur. MAO inhibitors include isocarboxazid, linezolid, phenelzine, rasagiline, selegiline, and tranylcypromine.
Get emergency medical help if you have any of these signs of an allergic reaction while taking chlorpheniramine/methscopolamine/phenylephrine: hives; difficult breathing; swelling of your face, lips, tongue, or throat.
Stop using this medicine and call your doctor at once if you have:
little or no urinating;
fast, pounding, or irregular heartbeats;
pale skin, weakness, feeling short of breath; or
tremors, hallucinations, severe anxiety.
Common side effects may include:
dry mouth, nose, or throat;
feeling nervous or restless.
This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects.
For Healthcare Professionals
Applies to chlorpheniramine/methscopolamine/phenylephrine: oral capsule extended release, oral liquid, oral suspension extended release, oral syrup, oral tablet, oral tablet chewable, oral tablet chewable extended release, oral tablet extended release
Nervous system side effects of phenylephrine have included headache, dizziness, nervousness, restlessness, tremor, insomnia, convulsions, and central nervous system depression. Antihistamines such as chlorpheniramine and anticholinergics such as methscopolamine may cause drowsiness and dizziness.[Ref]
Psychiatric side effects of phenylephrine have included hallucinations, fear, and anxiety.[Ref]
Gastrointestinal side effects of phenylephrine have included nausea. Antihistamines such as chlorpheniramine and anticholinergics such as methscopolamine may cause excessive dryness of the nose, throat, and mouth.[Ref]
Respiratory side effects of phenylephrine have included respiratory difficulty.[Ref]
General side effects of phenylephrine have included pallor and weakness.[Ref]
More about Omnihist L.A. (chlorpheniramine / methscopolamine / phenylephrine)
- Drug interactions
- Dosage information
- During pregnancy
- Drug images
- Drug class: upper respiratory combinations
Related treatment guides
1. "Product Information. Ah-Chew D (phenylephrine)." WE Pharmaceuticals Inc (2002):
2. "Product Information. Drize (chlorpheniramine/methscopolamine/PE)." King Pharmaceuticals Inc (2022):
3. "PDR Generics." Montvale, NJ: Medical Economics (1998):
Some side effects may not be reported. You may report them to the FDA.