Hetlioz and Flexeril drug interactions - a phase IV clinical study of FDA data

Summary:

Drug interactions are reported among people who take Hetlioz (tasimelteon) and Flexeril (cyclobenzaprine hydrochloride). Common drug interactions include drug ineffective among females and insomnia among males.

The phase IV clinical study analyzes what interactions people have when they take Hetlioz and Flexeril. It is created by eHealthMe based on reports of 25 people who take the same drugs from the FDA, and is updated regularly.

What is Hetlioz?

Hetlioz has active ingredients of tasimelteon. eHealthMe is studying from 7,418 Hetlioz users. Check the latest studies of Hetlioz.

What is Flexeril?

Flexeril has active ingredients of cyclobenzaprine hydrochloride. It is often used in muscle spasms. eHealthMe is studying from 38,308 Flexeril users. Check the latest studies of Flexeril.

On Jul, 30, 2026

25 people who take Hetlioz and Flexeril together, and have interactions are studied.

What are the common drug interactions of Hetlioz and Flexeril, by gender? *:

female:

Drug ineffective
Insomnia (sleeplessness)
Malaise (a feeling of general discomfort or uneasiness)
Influenza
Nightmare (unpleasant dream)
Adverse event
Cellulitis (infection under the skin)
Constipation
Dizziness
Drug effect decreased

male:

Insomnia (sleeplessness)
Drug ineffective
Asthenia (weakness)
Dehydration (dryness resulting from the removal of water)
Dry mouth
Dyspnoea (difficult or laboured respiration)
Gait disturbance
Gastrointestinal viral infection (virus infection of gastrointestinal tract)
Heart rate increased
Initial insomnia (feeling of inadequate or poor-quality sleep)

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

0-1:

n/a

2-9:

n/a

10-19:

n/a

20-29:

n/a

30-39:

n/a

40-49:

Dizziness
Headache (pain in head)
Insomnia (sleeplessness)
Malaise (a feeling of general discomfort or uneasiness)
Middle insomnia (difficulty returning to sleep after awakening either in the middle of the night)
Nausea (feeling of having an urge to vomit)
Nightmare (unpleasant dream)
Vomiting

50-59:

Drug ineffective
Insomnia (sleeplessness)
Drug effect decreased
Initial insomnia (feeling of inadequate or poor-quality sleep)

60+:

Drug ineffective
Middle insomnia (difficulty returning to sleep after awakening either in the middle of the night)
Asthenia (weakness)
Cellulitis (infection under the skin)
Constipation
Dehydration (dryness resulting from the removal of water)
Dry mouth
Dyspnoea (difficult or laboured respiration)
Gait disturbance
Gastrointestinal viral infection (virus infection of gastrointestinal tract)

What are the existing conditions these people have? *

Circadian Rhythm Sleep Disorder (family of sleep disorders affecting, among other things, the timing of sleep): 9 people, 36.00%
Restless Leg Syndrome (a powerful urge to move your legs): 2 people, 8.00%
Arthritis (form of joint disorder that involves inflammation of one or more joints): 2 people, 8.00%

* Approximation only. Some reports may have incomplete information.

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