This article is from the Children Allergies and Asthma FAQ, by Eileen Kupstas Soo firstname.lastname@example.org with numerous contributions by others.
Yes. Epenephrine or adrenaline is usually effective at suppressing the
allergic reaction immediately, although severe reactions may require a
second dose. Later in the process, you may need an antihistamine
like Benadryl (the over-the-counter preparation may not be strong
enough). Your medical professional can help you in evaluating your
need for this and obtaining it.