The following side effects may get better over time as your body gets used to the medication. Let your healthcare provider know immediately if you continue to experience these symptoms or if they worsen over time.
Common Side Effects
The following side effects are those reported with dextromethorphan:
- Drowsiness
- Dizziness
- Stomach upset
The following side effects are those reported with promethazine:
- Feeling drowsy or tired
- Dizziness
- Blurry vision
- Dry mouth
- Nausea
- Vomiting
Less Common Side Effects
The following side effects are those reported with promethazine:
- Feeling agitated
- Excitement
- Uncontrollable body movements
- Trouble maintaining balance
- Changes in heart rate
- Sensitivity to light
- Hives
- Nightmares
- Trouble sleeping
Promethazine DM serious side effects
Contact your healthcare provider immediately if you experience any of the following.
- Neuroleptic malignant syndrome (NMS): stiff muscles, high fever, sweating, changes in heartbeat, changes in heart rhythm, confusion
- Breathing problems: stuffy nose, slowed breathing, breathing repeatedly stops
- Brain-related problems: excess sleepiness, blurry or double vision, confusion, ringing in ears, hallucinations, seizures, hysteria, uncontrolled movements, tremors
- Overdose: confusion, hallucination, dizziness, breathing problems, coma, sudden death
When do Promethazine DM possible side effects begin and end?
Time passed since treatment started:
M
H
D
W
M
Drowsiness
Dizziness
Confusion
Stomach upset
Blurry vision
Trouble breathing
Seek immediate medical care if you experience this side effect.
Source: DailyMed
The following Promethazine DM side effects have also been reported
Side effects that you should report to your care team as soon as possible:
- Allergic reactions—skin rash, itching, hives, swelling of the face, lips, tongue, or throat
- CNS depression—slow or shallow breathing, shortness of breath, feeling faint, dizziness, confusion, trouble staying awake
- High fever, stiff muscles, increased sweating, fast or irregular heartbeat, and confusion, which may be signs of neuroleptic malignant syndrome
- Infection—fever, chills, cough, or sore throat
- Sudden eye pain or change in vision such as blurry vision, seeing halos around lights, vision loss
- Trouble passing urine
- Uncontrolled and repetitive body movements, muscle stiffness or spasms, tremors or shaking, loss of balance or coordination, restlessness, shuffling walk, which may be signs of extrapyramidal symptoms (EPS)
Side effects that usually do not require medical attention (report these to your care team if they continue or are bothersome):
- Confusion
- Constipation
- Dizziness
- Drowsiness
- Dry mouth
- Fatigue
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