Zyrtec and Lactase drug interactions - a phase IV clinical study of FDA data

Summary:

Drug interactions are reported among people who take Zyrtec (cetirizine hydrochloride) and Lactase (lactase). Common drug interactions include hypothyroidism among females and diarrhoea among males.

The phase IV clinical study analyzes what interactions people have when they take Zyrtec and Lactase. It is created by eHealthMe based on reports of 70 people who take the same drugs from the FDA, and is updated regularly.

What is Zyrtec?

Zyrtec has active ingredients of cetirizine hydrochloride. It is often used in allergies. eHealthMe is studying from 114,619 Zyrtec users. Check the latest studies of Zyrtec.

What is Lactase?

Lactase has active ingredients of lactase. It is often used in lactose intolerance. eHealthMe is studying from 948 Lactase users. Check the latest studies of Lactase.

On Jul, 11, 2026

70 people who take Zyrtec and Lactase together, and have interactions are studied.

What are the common drug interactions of Zyrtec and Lactase, by gender? *:

female:

Hypothyroidism (abnormally low activity of the thyroid gland, resulting in retardation of growth and mental development)
Psoriasis (immune-mediated disease that affects the skin)
Abdominal pain lower
Abdominal pain upper
Abdominal tenderness
Anxiety
Asthenia (weakness)
Chills (felling of cold)
Confusional state
Crohn's disease (a condition that causes inflammation of the gastrointestinal tract)

male:

Diarrhoea
Hypersensitivity
Blood pressure increased
Drug hypersensitivity
Headache (pain in head)
Infection
Intervertebral disc degeneration (spinal disc degeneration)
Osteoarthritis (a joint disease caused by cartilage loss in a joint)
Anastomotic complication (complication of surgical connection between two structures)
Anxiety

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

0-1:

n/a

2-9:

Dehydration (dryness resulting from the removal of water)
Intestinal obstruction
Scar
Sinusitis (inflammation of sinus)

10-19:

Alopecia (absence of hair from areas of the body)
Crohn's disease (a condition that causes inflammation of the gastrointestinal tract)
Diarrhoea

20-29:

Bronchitis (inflammation of the mucous membrane in the bronchial tubes)
Nausea (feeling of having an urge to vomit)
Sinusitis (inflammation of sinus)
Sleep apnoea syndrome (a sleep-related disorder in which the effort to breathe is diminished or absent)
Upper respiratory tract infection
Heart valve incompetence (heart's valves do not work correctly)
Irritable bowel syndrome
Mitral valve incompetence (inefficient heart valve)
Pulmonary arterial pressure increased
Right atrial dilatation (enlargement of the right atrium chamber of heart)

30-39:

Abdominal pain lower
Alopecia (absence of hair from areas of the body)
Eating disorder
Hepatic enzyme increased
Nausea (feeling of having an urge to vomit)
Systemic lupus erythematosus (an autoimmune disease, which means the body's immune system mistakenly, attacks healthy tissue)

40-49:

Abdominal pain
Dizziness
Nausea (feeling of having an urge to vomit)
Anaphylactic shock (severe and rapid and sometimes fatal hypersensitivity reaction to a substance)
Antibody test positive
Automatic bladder (nerve impulses between the bladder and the spinal cord remain intact and the bladder can be trained to empty by reflex (spastic) action)
Breast cancer stage ii
Electrocardiogram qt prolonged
Gallbladder polyp (growths or lesions resembling growths (polypoid lesions) in the wall of the gallbladder)
Hypothyroidism (abnormally low activity of the thyroid gland, resulting in retardation of growth and mental development)

50-59:

Muscular weakness (muscle weakness)
Nausea (feeling of having an urge to vomit)
Pain in extremity
Pyrexia (fever)
Rhinorrhoea (watery mucus discharge from the nose)
Sinus disorder (disease of sinus)
Blister (small pocket of fluid within the upper layers of the skin caused by forceful rubbing (friction), burning, freezing, chemical exposure)
Hypersensitivity
Implant site erosion
Implant site inflammation

60+:

Diarrhoea
Abdominal discomfort
Thrombosis (formation of a blood clot inside a blood vessel)
Vertigo
Vomiting
Arthralgia (joint pain)
Nausea (feeling of having an urge to vomit)
Anastomotic complication (complication of surgical connection between two structures)
Anxiety
Body height decreased

What are the existing conditions these people have? *

Multiple Myeloma (cancer of the plasma cells): 13 people, 18.57%
Narcolepsy (brain's inability to regulate sleep-wake cycles normally): 10 people, 14.29%
Cataplexy (loss of muscle tone accompanied by full conscious awareness): 10 people, 14.29%
Muscle Spasticity (tight or stiff muscles and an inability to control those muscles): 8 people, 11.43%
Immunodeficiency Common Variable: 8 people, 11.43%
Drowsiness: 8 people, 11.43%
Asthma: 5 people, 7.14%
Primary Pulmonary Hypertension (primary high blood pressure that affects the arteries in the lungs and the right side of your heart): 4 people, 5.71%
Pain: 4 people, 5.71%
Nausea (feeling of having an urge to vomit): 4 people, 5.71%

* Approximation only. Some reports may have incomplete information.

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