Phenergan and Sinemet drug interactions - a phase IV clinical study of FDA data

Summary:

Drug interactions are reported among people who take Phenergan (promethazine hydrochloride) and Sinemet (carbidopa; levodopa). Common drug interactions include anxiety among females and major depression among males.

The phase IV clinical study analyzes what interactions people have when they take Phenergan and Sinemet. It is created by eHealthMe based on reports of 96 people who take the same drugs from the FDA, and is updated regularly.

What is Phenergan?

Phenergan has active ingredients of promethazine hydrochloride. It is often used in nausea. eHealthMe is studying from 25,312 Phenergan users. Check the latest studies of Phenergan.

What is Sinemet?

Sinemet has active ingredients of carbidopa; levodopa. It is often used in parkinson's disease. eHealthMe is studying from 29,601 Sinemet users. Check the latest studies of Sinemet.

eHealthMe: drug outcomes in the real world

eHealthMe runs one of the largest post-marketing drug safety studies in the world. We study millions of patients and 5,000 more each day. Our data-driven phase IV clinical trials have been referenced on 800+ peer-reviewed medical publications including The Lancet, Mayo Clinic Proceedings, and Nature. Tools to study our phase IV findings are available to the public, anonymous and free >>>.

On Aug, 21, 2026

96 people who take Phenergan and Sinemet together, and have interactions are studied.

Phenergan and Sinemet drug interactions.

What are the common drug interactions of Phenergan and Sinemet, by gender? *:

female:

Anxiety
Diarrhoea
Catatonia (unresponsive to external stimuli)
Fatigue (feeling of tiredness)
Hypoaesthesia (reduced sense of touch or sensation)
Pyrexia (fever)
Dizziness
Tremor (trembling or shaking movements in one or more parts of your body)
Abdominal pain
Acute myocardial infarction (acute heart attack)

male:

Major depression (a mood state that goes well beyond temporarily feeling sad or blue. it is a serious medical illness that affects one's thoughts, feelings)
Obsessive-compulsive disorder (an anxiety disorder characterized by intrusive thoughts that produce uneasiness, apprehension, fear, or worry;)
Anxiety
Asthenia (weakness)
Cough
Myocardial infarction (destruction of heart tissue resulting from obstruction of the blood supply to the heart muscle)
Oedema peripheral (superficial swelling)
Pyrexia (fever)
Ventricular extrasystoles (premature cardiac contraction)
Pneumonia

What are the common drug interactions of Phenergan and Sinemet, by age (0-1 to 60+)? *:

0-1:

n/a

2-9:

n/a

10-19:

n/a

20-29:

Drug hypersensitivity
Fibromyalgia (a long-term condition which causes pain all over the body)
Gastroenteritis viral (inflammation of stomach and intestine caused by virus infection)
Hypercoagulation (increased tendency for clotting of the blood)
Neuralgia (pain in one or more nerves)
Suicidal ideation
Erythema (redness of the skin)
Oxygen saturation decreased
Post procedural complication
Pruritus (severe itching of the skin)

30-39:

Pulmonary embolism (blockage of the main artery of the lung)

40-49:

Arthralgia (joint pain)
Headache (pain in head)
Depression
Hypoaesthesia (reduced sense of touch or sensation)
Tremor (trembling or shaking movements in one or more parts of your body)
Weight decreased
Abdominal pain
Candidiasis (candidiasis or thrush is a fungal infection)
Cellulitis (infection under the skin)
Confusional state

50-59:

Otitis externa (external ear infection)
Presbyopia (a condition in which the lens of the eye loses its ability to focus, making it difficult to see objects up close)
Pyrexia (fever)
Schizoaffective disorder (a mental disorder characterized by disordered thought)
Tendonitis (a condition that causes pain and swelling of tendons)
Type 2 diabetes mellitus
Vaginal infection
Otitis media (inflammation of the middle ear)
Diarrhoea
Urinary tract infection

60+:

Fatigue (feeling of tiredness)
Catatonia (unresponsive to external stimuli)
Pneumonia
Adverse drug reaction
Dyspnoea (difficult or laboured respiration)
Hallucination (an experience involving the perception of something not present)
Arthralgia (joint pain)
Fall
Cough
Constipation

What are the existing conditions these people have? *

Pain: 23 people, 23.96%
Depression: 12 people, 12.50%
Stress And Anxiety: 10 people, 10.42%
Hypersensitivity: 9 people, 9.38%
Gastroesophageal Reflux Disease (a condition in which stomach contents leak backward from the stomach into the oesophagus): 9 people, 9.38%
Restless Leg Syndrome (a powerful urge to move your legs): 7 people, 7.29%
Wheezing (a high-pitched whistling sound made while you breath): 6 people, 6.25%
Insomnia (sleeplessness): 6 people, 6.25%
Nausea And Vomiting: 5 people, 5.21%
Dyspnea (difficult or laboured breathing): 5 people, 5.21%

* Approximation only. Some reports may have incomplete information.

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