Consumer medicine information

Snuzaid Tabs

Diphenhydramine hydrochloride


Brand name

Snuzaid Tabs

Active ingredient

Diphenhydramine hydrochloride




Consumer medicine information (CMI) leaflet

Please read this leaflet carefully before you start using Snuzaid Tabs.

What is in this leaflet?

This leaflet answers some common questions about SNUZAID ®TABS.

It does not contain all the available information.

It does not take the place of talking to your doctor or pharmacist.

If you have any concerns about taking this medicine, consult your doctor or pharmacist.

Keep this leaflet with your medicine. You may need to read it again.

What SNUZAID®TABSare used for

SNUZAID®TABS help relieve insomnia. They are intended for short term use to re-establish regular sleep patterns. Do not use them for more than ten days consecutively.

What is insomnia?

Insomnia is having trouble getting to sleep or staying asleep. It may also be the feeling that you are not getting enough sleep.

What causes insomnia?

Insomnia may be caused by some or all of the following:

  • stress
  • noise
  • late night eating
  • late night exercise
  • inactive lifestyle
  • drinking too much tea, coffee or cola
  • taking medicines containing stimulants such as cold medicines

How do SNUZAID®TABS work?

SNUZAID®TABS belong to a group of medicines called antihistamines. Some antihistamines, including diphenhydramine cause the central nervous system to slow down and this provides relief for insomnia.

There is no evidence that SNUZAID®TABS are addictive.

Establishing Regular Sleep Patterns

In addition to taking SNUZAID®TABS, the following good sleep habits must be established and maintained.

  • go to bed and rise at the same time daily
  • engage in relaxing activities before bedtime
  • exercise regularly but not late in the evening
  • avoid eating meals or large snacks just before bedtime
  • eliminate day time naps
  • avoid caffeine containing drinks after midday
  • avoid alcohol or the use of nicotine late in the evening
  • minimise external disruption (eg. light and noise)
  • if you are unable to sleep, do not become anxious; leave the bedroom and participate in relaxing activities such as reading or listening to music until you are tired

Before you take SNUZAID®TABS

Do not take SNUZAID®TABS if you have ever had an allergic reaction to :

  • SNUZAID®TABS or any of the ingredients listed at the end of this leaflet.
  • Other medications containing antihistamines eg. travel sickness preparations such as Dramamine

Do not take SNUZAID®TABS if you have, or have had any of the following medical conditions:

  • asthma
  • chronic bronchitis
  • severe liver or kidney disease
  • closed -angle glaucoma
  • prostate problems
  • difficulty passing urine
  • a narrowing or blockage between the stomach and small intestine which causes vomiting of undigested food
  • epilepsy
  • porphyria

Do not take SNUZAID®TABS if you are taking or being given any of the following medicines as they may interfere with each other:

  • antidepressant medicines known as monoamine oxidase inhibitors (MAOI's). These include moclobemide(Arima,Aurorix),phenelzine(Nardil) and tranylcypromine(Parnate)
  • tricyclic antidepressant medicines such as amitriptyline(Tryptanol) imipramine(Melipramine), nortriptyline(Allegron) and doxepin(Deptran)
  • strong pain killers such as codeine and morphine.
  • other medicines used to help you sleep including temazepam(Temaze, Normison) triazolam(Halcion) or nitrazepam(Mogadon)
  • medicines used to treat anxiety such as oxazepam(Serapax) or diazepam(Valium)
  • antibiotics known as aminoglycosides such as tobramycin

Do not take SNUZAID®TABS if you are pregnant or intend to become pregnant.

Like most antihistamine medicines SNUZAID®TABS are not recommended for use during pregnancy. SNUZAID®TABS are not known to cause birth defects but studies to prove they are safe for the developing baby have not been done.

Do not take SNUZAID®TABS if you are breast feeding or plan to breast feed.

Small amounts of SNUZAID®TABS pass into breast milk. There is a possibility that the breast fed baby may become unusually excited or irritable. It is also possible that breast milk supply will be affected.

Do not give SNUZAID®TABS to a child under 12 years of age.

Do not take SNUZAID®TABS after the expiry date (EXP) printed on the pack.

If you take this medicine after the expiry date has passed, it may not work as well.

Do not take SNUZAID®TABS if the packaging is torn or shows signs of tampering.

While you are using SNUZAID®TABS

Things to be careful of:

Drowsiness on the day following use may occur.

Use extreme care while doing anything that involves complete alertness such as driving a car, operating machinery, or piloting an aircraft.

Be careful drinking alcohol while taking SNUZAID®TABS as the effects of drowsiness and uncoordination may be increased

How to take SNUZAID®TABS

SNUZAID®TABS will cause drowsiness and should be used only at bedtime.


Take one (1) tablet 20 minutes before bed when necessary. Swallow with a glass of water.

Follow all directions given to you by your doctor or pharmacist carefully.

They may differ from the information contained in this leaflet.

How long to take it

Do not take SNUZAID®TABS for more than ten days. If sleeplessness persists continuously for longer than this tell your doctor. Insomnia might be a sign of another medical problem.

Side Effects

SNUZAID®TABS help most people with sleeplessness, but they may have unwanted side effects in a few people. All medicines can have side effects. Sometimes they are serious, most of the time they are not. If you are over 65 years of age you may have an increased chance of getting side effects.

These are the more common side effects of SNUZAID®TABS. Mostly these are mild and short lived.

  • drowsiness on the day following use
  • dizziness
  • uncoordination
  • dry mouth, nose and/or throat
  • headache
  • muscle weakness
  • thicker nasal discharge

Do not be alarmed by this list of possible side effects. You may not experience any of them.

Other side effects not listed above may occur in some patients. Tell your doctor or pharmacist if you notice anything that is making you feel unwell.

Serious side effects are rare.

Tell your doctor immediately if you notice any of the following:

  • fast, pounding heartbeats
  • difficulty passing urine
  • constipation
  • tremors
  • nervousness
  • restlessness
  • nightmares
  • ringing in the ears
  • excitation
  • faintness
  • blurred vision
  • increased gastric reflux


If you think that you or anyone else may have taken too many SNUZAID®TABS ,immediately contact your doctor, pharmacist or the Poisons Information Centre (telephone 13 11 26).

Do this even if there are nosigns of discomfort or poisoning

If you have taken too many SNUZAID®TABS you may suffer;

  • severe drowsiness
  • severe dryness of the mouth, nose and throat
  • flushing or redness in the face
  • fast, pounding or irregular heartbeats
  • shortness of breath
  • hallucinations
  • seizures
  • convulsions
  • insomnia
  • dilated pupils
  • delirium

After using SNUZAID®TABS


Keep your tablets in a cool dry place where the temperature stays below 30°C.

Do not store them or any other medicine in the bathroom or near a sink.

Keep it where children cannotreach it.

Product Description

SNUZAID®TABS are round, white tablets with a break bar on one side.

Active ingredients:

Diphenhydramine hydrochloride 50 mg per tablet.

Other ingredients:

  • cellulose-microcrystalline
  • crospovidone
  • povidone
  • silica-colloidal anhydrous
  • starch-pregelatinised maize
  • magnesium stearate


SNUZAID®TABS are made for
H.W.Woods Pty.Ltd
8 Clifford Street
VIC 3166

Australian Registration Number: 129483

This leaflet was prepared in July 2004.


Brand name

Snuzaid Tabs

Active ingredient

Diphenhydramine hydrochloride




Name of the medicine

Diphenhydramine hydrochloride.


Microcrystalline cellulose, crospovidone, povidone, anhydrous colloidal silica, pregelatinised maize starch and magnesium stearate.


Chemical name: 2-(diphenylmethoxy) -N,N-dimethylethylamine hydrochloride. Molecular formula: C17H21NOHCl. MW: 291.82. Diphenhydramine hydrochloride is a water soluble, white, odourless, crystalline powder.


Diphenhydramine is a H1-receptor antagonist antihistamine belonging to the ethanolamine group.


This group characteristically produces pronounced sedative effects with low incidence of gastrointestinal disturbance. The significant sedative properties result from inhibition of histamine-N-methyl transferase and blockage of the central histaminergic receptors. Antagonism of other CNS (central nervous system) receptor sites such as those for serotonin, acetylcholine and α-adrenergic stimulation may be involved. Anticholinergic activity at muscarinic receptors also occurs.


Diphenhydramine is well absorbed after oral administration. It is distributed throughout the body with high concentrations found in the lungs. It is up to 85% protein bound (76% in Asians). The volume of distribution (Vd) is in the range 3.3 to 6.9 L/kg (6.9 L/kg for Asians). The high Vd for Asians may be explained by the reduced protein binding.
In one study, following administration of an oral dose of 50 mg, the peak plasma concentration was measured at 66 nanogram/mL after 2.3 hours. Other studies show peak concentrations occur between two and four hours with duration of activity between four and six hours. The terminal elimination half-life ranges between three and nine hours.
Metabolism occurs in the liver via the P450 system. A high first-pass effect is observed following oral administration with at least half metabolised before reaching the general circulation.
Approximately 65% of a dose is excreted in the urine within four days, almost entirely as metabolites. Two successive N-demethylations occur to produce a primary amine, which is further oxidised to diphenylmethoxyacetic acid. This appears in the urine as glutamine and glucuronide conjugates as well as in the unconjugated form. Less than 1% is excreted unchanged in the urine. None of the metabolites are active.


Temporary relief of insomnia.


Hypersensitivity to diphenhydramine or any other component. Diphenhydramine should not be given to newborn infants due to their heightened sensitivity towards anticholinergic side effects. It is contraindicated in patients with severe hepatic, renal or respiratory insufficiency.


Avoid concurrent use with alcohol and other medications which suppress the central nervous system as the effects of both may be enhanced.
A risk/ benefit approach should be adopted for patients with glaucoma. Increased ocular pressure could precipitate an attack of angle closure glaucoma. Use with caution in patients with bladder neck obstruction, urinary retention, chronic bronchitis, stenosing peptic ulcer, pyloroduodenal obstruction, symptomatic prostatic hypertrophy, porphyria, asthma and epilepsy. The antiemetic properties of diphenhydramine may mask the symptoms of certain serious medical conditions, e.g. appendicitis.

Impaired renal function

Use with caution. Dosage reduction may be necessary.

Impaired hepatic function

Use with caution. Dosage reduction may be necessary. The elimination half-life in cirrhotic patients has been demonstrated to be longer in one study.

Use in the elderly

Use with caution due to enhanced susceptibility to adverse effects.

Carcinogenesis, mutagenesis, impairment of fertility

Carcinogenicity/ mutagenicity.

Long-term animal studies to evaluate the carcinogenic and mutagenic potential have not been performed.

Use in pregnancy.

(Category A)
Do not use during pregnancy. Diphenhydramine crosses the placenta. Therapeutic doses during pregnancy are considered unlikely to pose a substantial teratogenic risk. Studies in rats and rabbits at doses up to five times the human dose have revealed no evidence of impaired fertility or harm to the fetus but no well controlled studies in pregnant women have been done.

Use in lactation.

Small amounts of diphenhydramine are excreted into breast milk. Use is not recommended because of the risk of adverse effects in infants, i.e. unusual excitement or irritability. Anticholinergic effects may inhibit lactation.

Use in children

Do not give to children under 12 years of age due to heightened sensitivity towards paradoxical stimulation.

Effect on ability to drive or operate machinery

Drowsiness and hangover effects may affect the ability to drive and operate machinery the day following use.


Anticholinergic effects are prolonged and intensified when used with MAOIs (monoamine oxidase inhibitors), tricyclic antidepressants and atropine-like drugs. Concurrent use with other sedatives (e.g. benzodiazepines and barbiturates), tranquillizers, opioid analgesics and antipsychotics enhances the effects of CNS depression. Use with ototoxic medications, e.g. aminoglycoside antibiotics, may mask the symptoms of ototoxicity. These include tinnitus, dizziness and vertigo.

Effect on laboratory tests

Diphenhydramine may inhibit the cutaneous histamine response. Discontinue at least 72 hours before skin testing begins.

Adverse Effects

More common reactions.

Dizziness, disturbed coordination, lassitude, headache, muscular weakness and psychomotor impairment. Anticholinergic effects include dry nose, throat and mouth and thickened respiratory tract secretions.

Less common reactions.

Paradoxical stimulation of the central nervous system may occur and is much more likely to occur in children. Symptoms are nervousness, restlessness, unusual excitement, tinnitus, nightmares and irritability. Other adverse effects include tachycardia, palpitations, increased sweating and hypotension (particularly in the elderly). Less common anticholinergic effects are blurred vision, urinary difficulty or retention, constipation and increased gastric reflux.

Dosage and Administration

1 tablet 20 minutes before bed when necessary. Do not use for more than ten nights consecutively as insomnia may be symptomatic of a serious underlying medical condition. Do not give to children under 12 years of age.



Symptoms of overdosage include severe drowsiness and dryness of the mouth, nose and throat, redness or flushing in the face, shortness of breath, tachycardia, cardiac arrhythmia, dilated pupils, delirium and seizures. Rhabdomyolysis is a possible complication.
In children, central nervous system stimulation predominates over depression causing ataxia, excitement, tremors, psychoses, hallucinations and convulsions.


Contact the Poisons Information Centre on 131 126 for advice.


Tablets, 50 mg (white): 10's.


Store below 30°C.

Poison Schedule