Hesperian Health Guides

Medicines for Allergy or Itching: Antihistamines

Itching, sneezing, and rashes caused by allergy can usually be treated with antihistamines. Any antihistamine works about as well as any other. So if you do not have chlorpheniramine or diphenhydramine, use another antihistamine in the right dose (this will vary for each drug). All antihistamines make people drowsy, but some more than others.

These drugs are not helpful for the common cold.

Antihistamines should be avoided during pregnancy. If they must be given, choose a “first generation” antihistamine such as chlorpheniramine or diphenhydramine, and give with plenty of water.

For a severe allergic reaction where there is difficulty breathing, epinephrine (adrenaline) is needed as well as antihistamines.

Chlorpheniramine, chlorphenamine


Chlorpheniramine is an antihistamine that reduces itching, sneezing, rashes, and other problems caused by allergies. It can be used after an insect bite, a mild allergy to a food or medicine, or for “hay fever” (sneezing and itchy eyes from pollen in the air).

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Sleepiness (but this is less likely than with other antihistamines).

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Do not give to pregnant women unless necessary. Do not give during an asthma attack.

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1 to 2 years: give 1 mg, 2 times a day until the child feels better.
3 to 5 years: give 1 mg, every 4 to 6 hours until the child feels better.
6 to 12 years: give 2 mg, every 4 to 6 hours until the person feels better.
Over 12 years: give 4 mg, every 4 to 6 hours until the person feels better.

For severe allergic reaction
First inject epinephrine. Follow with chlorpheniramine by mouth in the doses listed to help prevent the reaction from coming back when the epinephrine wears off.

Diphenhydramine


Diphenhydramine is an antihistamine that reduces itching, sneezing, rashes, and other problems caused by allergies. It can be used after an insect bite, a mild food or drug allergy, or for “hay fever” (sneezing and itchy eyes from pollen in the air).

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Sleepiness.

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  • Diphenhydramine may cause dizziness, sleepiness or blurred vision. Do not drive or operate machinery if using this medicine. Drinking alcohol may increase the sleepiness caused by diphenhydramine.
  • Do not give to newborn babies or women who are breastfeeding. It is best not to give diphenhydramine to pregnant women unless necessary.
  • Do not give during an asthma attack.
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The dose is the same for giving diphenhydramine by mouth or as an injection into the muscle.
2 to 5 years: give 6 mg every 4 to 6 hours. Do not give more than 37 mg per day.
6 to 11 years: give 12 to 25 mg every 4 to 6 hours. Do not give more than 150 mg per day.
Over 12 years: give 25 to 50 mg every 4 to 6 hours. Do not give more than 400 mg per day.

For severe allergic reaction

First inject epinephrine. Following with diphenhydramine in the doses listed will help prevent the reaction from coming back when the epinephrine wears off.
2 to 11 years: give 1 to 2 mg per kg, every 6 hours. If you cannot weigh the child, use the doses
by age listed above, and give the larger amount. Do not give more than 50 mg at one time, or
300 mg per day.
Over 12 years: give 25 to 50 mg, every 2 to 4 hours. Do not give more than 100 mg in 4 hours
or 400 mg per day.

Epinephrine (adrenaline)


Epinephrine is used for severe allergic reaction (anaphylaxis) to medicines, foods, insect stings or bites, or other things that cause a severe allergic reaction. It helps reverse the effects such as difficulty breathing, wheezing, severe skin itching, and hives.

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Fear, restlessness, nervousness, tension, headaches, dizziness, increased heart rate.

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Epinephrine often comes in ampules of 1 mg per 1 ml liquid. Epinephrine is also available in preloaded autoinjectors, but these come in different amounts. Be sure to read to see how much epinephrine is in your autoinjector to make sure you are giving the correct amount.

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For severe allergic reaction

Inject into the muscle in the outer part of the mid-thigh.
1 to 5 years: inject ¼ mg (0.25 mg).
6 to 12 years: inject ⅓ mg (0.33 mg).
Over 12 years: inject ½ mg (0.5 mg).

If needed, you can give a second dose in 5 to 15 minutes, and a third dose in 5 to 15 minutes after that. Do not give more than 3 doses.

After giving epinephrine, give an antihistamine such as chlorpheniramine or diphenhydramine. This will help prevent the reaction from coming back when the epinephrine wears off.

Salbutamol (albuterol)


Salbutamol relaxes the muscles in the airway to increase air flow to the lungs. It is used to treat wheezing or shortness of breath from asthma or inhaling a lot of smoke from a fire.

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Trembling, nervousness, dizziness, fast heartbeat, and headaches.

How to use

Give 2 puffs from an inhaler (200 micrograms) every 4 to 6 hours as needed. Use with a spacer for better effects.

It is OK to give more than the amounts listed above if the person feels they need it.


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This page was updated:01 Feb 2021