Indications
Dimenhydrinate is an antihistamine used to prevent and treat nausea, vomiting and dizziness caused by motion sickness (travel by car, bus, boat or plane). It is also used for vertigo and inner ear balance problems, often in combination with Cinnarizine.
How It Works
Dimenhydrinate is a combination of Diphenhydramine and a mild stimulant. Diphenhydramine blocks histamine and acetylcholine signals in the balance centre of the inner ear and in the part of the brain that triggers vomiting. This calms the mixed signals that cause travel sickness and vertigo. When combined with Cinnarizine, the two work together to improve dizziness.
Dosage and Administration
Adults: 50 to 100 mg every 4 to 6 hours as needed, not more than 400 mg in 24 hours. For travel sickness, take the first dose 30 to 60 minutes before the journey. Combination tablets with Cinnarizine are usually taken as one tablet up to three times daily, or as directed on the label or by a doctor. Children’s doses are set by a doctor; it is not usually given to children under 2 years.
Interactions
- Alcohol, sleeping tablets, sedating antihistamines, opioid pain relievers and anxiety medicines increase drowsiness.
- Other anticholinergic medicines, such as tricyclic antidepressants, can add to dry mouth, constipation and urinary retention.
- It may hide early signs of ear damage caused by medicines such as Gentamicin.
Contraindications
- Allergy to Dimenhydrinate, Diphenhydramine or other similar antihistamines.
- Narrow angle glaucoma.
- Porphyria.
- Babies under 2 years unless advised by a doctor.
Side Effects
Drowsiness is the most common effect. Others include dry mouth, blurred vision, dizziness, headache, constipation and difficulty passing urine. Children and older people may sometimes become restless or excited instead of sleepy.
Get urgent medical help if you have a fast or irregular heartbeat, confusion or hallucinations, fits, inability to pass urine, or swelling of the face or throat or trouble breathing.
Pregnancy and Lactation
It is sometimes used for nausea in pregnancy, but only on a doctor’s advice. Small amounts pass into breast milk and may make the baby drowsy or reduce milk supply, so ask your doctor before using while breastfeeding.
Precautions and Warnings
- It causes drowsiness: do not drive or operate machines after taking it.
- Use with care in enlarged prostate, asthma, epilepsy, heart disease, liver disease and in older people.
- Avoid alcohol.
Overdose
Overdose can cause severe drowsiness, confusion, dilated pupils, fast heartbeat, high temperature, fits and, in children, excitement and hallucinations. Seek emergency medical help.
Therapeutic Class
Antihistamine antiemetic (H1 receptor antagonist).
Storage
Store below 30°C in a dry place, away from light and out of the reach of children.
Prepared by the Oshud Alo team from standard drug references. For information only; always follow your doctor's advice.