Pepcid and Firdapse drug interactions - a phase IV clinical study of FDA data

Summary:

Drug interactions are reported among people who take Pepcid (famotidine) and Firdapse (amifampridine). Common drug interactions include dizziness among females and intestinal obstruction among males.

The phase IV clinical study analyzes what interactions people have when they take Pepcid and Firdapse. It is created by eHealthMe based on reports of 45 people who take the same drugs from the FDA, and is updated regularly.

What is Pepcid?

Pepcid has active ingredients of famotidine. It is often used in gastroesophageal reflux disease. eHealthMe is studying from 55,774 Pepcid users. Check the latest studies of Pepcid.

What is Firdapse?

Firdapse has active ingredients of amifampridine. eHealthMe is studying from 2,112 Firdapse users. Check the latest studies of Firdapse.

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, 24, 2026

45 people who take Pepcid and Firdapse together, and have interactions are studied.

What are the common drug interactions of Pepcid and Firdapse, by gender? *:

female:

Dizziness
Sudden death
Flank pain (a distressing sensation experienced around the lower back and the upper abdomen)
Haematuria (presence of blood in urine)
Haemoglobin decreased
Adjustment disorder with depressed mood
Chest discomfort
Depressed mood
Dysphagia (a condition in which swallowing is difficult or painful)
Emotional distress

male:

Intestinal obstruction
Road traffic accident
Dizziness
Hypoaesthesia oral (reduced sense of touch or sensation in mouth)
Hyporeflexia (a condition of below normal or absent reflexes)
Myasthenic syndrome (a group of conditions characterized by muscle weakness (myasthenia) that worsens with physical exertion)
Paraesthesia (sensation of tingling, tickling, prickling, pricking, or burning of a person's skin with no apparent long-term physical effect)
Sinus congestion (blockage of sinus)
Weight decreased
Bacteraemia (presence of bacteria in the blood)

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

0-1:

n/a

2-9:

n/a

10-19:

n/a

20-29:

Hypophagia (reduced food intake)
Influenza
Nausea (feeling of having an urge to vomit)
Therapeutic response unexpected
Vomiting

30-39:

Dizziness
Drug ineffective
Headache (pain in head)
Cystitis (inflammation of the wall of the bladder)
Gastritis (inflammation of stomach)
Haemorrhoids (a swollen vein or group of veins in the region of the anus)
Hyperbilirubinaemia (excess of bilirubin in the blood)
Hypertransaminasaemia
Iron deficiency anaemia
Rectal haemorrhage (bleeding from anus)

40-49:

n/a

50-59:

Emotional distress
Exercise tolerance decreased
Eyelid disorder
Gait disturbance
Mobility decreased (ability to move is reduced)
Muscle tightness
Muscular weakness (muscle weakness)
Nervousness
Quality of life decreased
Respiratory muscle weakness

60+:

Septic shock (shock due to blood infection)
Asthenia (weakness)
Proteus infection (proteus can cause urinary tract infections)
Tremor (trembling or shaking movements in one or more parts of your body)
Urinary tract infection
Anaemia (lack of blood)
Performance status decreased
Klebsiella sepsis (klebsiella causes a potentially fatal whole-body inflammation)
Nephropathy toxic (damage to kidney due to toxins)
Diabetes mellitus (diabetes, caused by a deficiency of the pancreatic hormone insulin)

What are the existing conditions these people have? *

Lambert-Eaton Syndrome (this means your immune system mistakenly targets healthy cells and tissues in the body): 44 people, 97.78%
Thyroid Cancer: 3 people, 6.67%

* Approximation only. Some reports may have incomplete information.

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