Arzerra and Benadryl drug interactions - a phase IV clinical study of FDA data

Summary:

Drug interactions are reported among people who take Arzerra (ofatumumab) and Benadryl (diphenhydramine hydrochloride). Common drug interactions include anaphylactic reaction among females and nausea among males.

The phase IV clinical study analyzes what interactions people have when they take Arzerra and Benadryl. It is created by eHealthMe based on reports of 41 people who take the same drugs from the FDA, and is updated regularly.

What is Arzerra?

Arzerra has active ingredients of ofatumumab. eHealthMe is studying from 1,042 Arzerra users. Check the latest studies of Arzerra.

What is Benadryl?

Benadryl has active ingredients of diphenhydramine hydrochloride. It is often used in allergies. eHealthMe is studying from 104,955 Benadryl users. Check the latest studies of Benadryl.

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, 17, 2026

41 people who take Arzerra and Benadryl together, and have interactions are studied.

What are the common drug interactions of Arzerra and Benadryl, by gender? *:

female:

Anaphylactic reaction (serious allergic reaction)
Arthralgia (joint pain)
Asthenia (weakness)
Balance disorder
Burning sensation
Chest discomfort
Dizziness
Dysphagia (a condition in which swallowing is difficult or painful)
Dysphonia (speech disorder attributable to a disorder of phonation)
Dyspnoea (difficult or laboured respiration)

male:

Nausea (feeling of having an urge to vomit)
Heart rate decreased
Sluggishness (lacking alertness)
Urticaria (rash of round, red welts on the skin that itch intensely)
Weight increased
Constipation
Dizziness
Eye haemorrhage (bleeding in the eye)
Fatigue (feeling of tiredness)
Hallucination (an experience involving the perception of something not present)

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

0-1:

n/a

2-9:

Diarrhoea
Drug administration error
Gait disturbance
Hypoxia (low oxygen in tissues)
Mental status changes (general changes in brain function, such as confusion, amnesia (memory loss), loss of alertness, loss of orientation)
Pneumonia viral
Somnolence (a state of near-sleep, a strong desire for sleep)

10-19:

Anaphylactic reaction (serious allergic reaction)
Dyspnoea (difficult or laboured respiration)
Erythema (redness of the skin)
Swelling face
Throat tightness

20-29:

n/a

30-39:

n/a

40-49:

Abdominal discomfort
Dizziness
Dyspepsia (indigestion)
Dysphagia (a condition in which swallowing is difficult or painful)
Dysphonia (speech disorder attributable to a disorder of phonation)
Feeling of body temperature change
Oropharyngeal pain
Progressive multifocal leukoencephalopathy (rapidly progressive neuromuscular disease caused by opportunistic infection of brain cells)
Pulmonary thrombosis (scarring in the lungs)
Rash

50-59:

Neutrophil count decreased (less than normal number of neutrophil a type of blood cell)
Neutrophil count increased (excess than normal number of neutrophil a type of blood cell)
Pain in jaw
Pneumonia
Pulmonary mass
Pulmonary oedema (fluid accumulation in the lungs)
Pyrexia (fever)
Retching (strong involuntary effort to vomit)
Sepsis (a severe blood infection that can lead to organ failure and death)
Somnolence (a state of near-sleep, a strong desire for sleep)

60+:

Nausea (feeling of having an urge to vomit)
Nervousness
Constipation
Erythema (redness of the skin)
Eye haemorrhage (bleeding in the eye)
Fatigue (feeling of tiredness)
Hallucination (an experience involving the perception of something not present)
Hyperhidrosis (abnormally increased sweating)
Urticaria (rash of round, red welts on the skin that itch intensely)
Chills (felling of cold)

What are the existing conditions these people have? *

Chronic Lymphocytic Leukaemia (cancer in which the bone marrow makes too many lymphocytes (a type of white blood cell)): 20 people, 48.78%
High Blood Pressure: 5 people, 12.20%

* Approximation only. Some reports may have incomplete information.

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