Aspirin and penicillin are the allopathic drugs used worldwide in bulk quantity. But these drugs may be allergic to certain individuals.
PENICILLIN ALLERGY
Allergic reactions to penicillin are very common. They range from urticaria to anaphylaxis; the later can cause death within minutes.
An anaphylactic reaction to penicillin, generally speaking, begins within seconds or a few minutes after taking it. The following sequence is typical—there is a peculiar taste in the mouth or a sensation in the tongue, and a strange tingling in the extremities.
Seconds later, there is severe constriction of the chest, and a choking sensation or dysnopea develops with increasing rapidity and cyanosis—bluish discolouration of the skin resulting from an increased amount of unoriginated haemoglobin in blood occurs simultaneously with symptoms of collapse. The whole reaction is sudden and terrifying. Only the alertness to the possible danger and instantaneous availability of the necessary injections and apparatus, can save the life of the patient.
TYPES OF REACTIONS
Anaphylactic reaction to penicillin is the most dangerous and the most dramatic; there are others which are less dramatic but more common. These may be categorised as follows :
DELAYED REACTION
This reaction is the most common one and it is thus called because of its incubation period, usually of 7 to 11 days; the minimum may be five days and the maximum perhaps about eight weeks. It is the response to initial sensitization and not to the previous exposure to penicillin. Urticaria is by far the most common symptom; others are joint pains, malaise and fever.
ACCELERATED AND IMMEDIATE REACTIONS
These reactions are much less frequent and occur only in patients who have been sensitized by previous exposure to penicillin. The accelerated reactions appear in a few hours or in two to three days, and the immediate type occurs within seconds or minutes or within two hours. Clinically, these vary from the mild to the, more often, severe. There may be urticaria, breathlessness and anaphylaxis.
HYPERALLERGIC REACTIONS
These are rare and include more intense and accelerated reactions with bullous eruptions—a thin walled air-filled space within the lung, arising congenitally or in emphysema.
CONTACT DERMATITIS
This follows the topical application of penicillin in the ointment form, but can manifest itself with other forms of application as well. The eruption may be acute, or chronic.
INDIRECT REACTIONS
Patients sensitive to penicillin are known to get reactions from it even from indirect sources. If a cow or a buffalo has been given a penicillin injection, even drinking its milk, by a patient sensitive to penicillin, is known to cause reactions. Some of the chronic reactions, such as urticaria may be perpetuated by penicillin through such indirect and often undetected sources.
Anaphylactic reaction to penicillin can occur not only after penicillin given by injection but also when it is administered orally in the form of a tablet, or instilled into the eye, ears or nose, or when applied on the skin as an ointment.
Those with a significant occurance of asthma in their families, and a similar personal history of either asthma or hay fever, usually have a higher incidence of penicillin reaction. Children show a lesser incidence of penicillin allergy than adults.
The commonest reaction to penicillin is appearance of rash over the body.
SKIN TEST WITH PENICILLIN
A positive skin test, observed at 15 minutes and most safely elicited by the scratch method, is a definite warning signal of potential anaphylaxis. When the case history suggests the possibility of anaphylaxis, the test is most safely carried out with graded dilutions beginning with 100 units per ml. and increasing to 50,000 units per ml.
If the scratch test is negative, then intracutaneous tests maybe carried out with dilutions of penicillin varying from 1000 to 50,000 units per ml. employing 0.2 ml. as is done in star allergy testing, to produce a just visible test weal.
The positive delayed skin test reaction, read like a tuberculin test (to know whether a person is infected with TB germs) after 24 to 48 hours, for redness and swelling in the skin occurs in those who have had a previous reaction to penicillin. This reaction is some times associated with urticaria or minute eruptions.
A careful note should be made of the fact that a negative skin test is no guarantee against adversereactions to penicillin.
PREVENTION
Penicillin should not be used unless absolutely necessary. Before prescribing or injecting penicillin, a careful history should be taken as to:
1. The frequency previous penicillin treatments as it is the repeated exposure to this antibiotic that is more likely to result in shock.
2. Any evidence of a previous allergic reaction to the antibiotic.
3. Personal history of allergy and especially of bronchial asthma.
4. Skin test by scratch method must be done.
Paradoxically, however, most patients who get anaphylactic shock have no past history of previous penicillin allergy, whatsoever.
An injection is best given in the outer arm rather than in the buttock so that, if need be, a tourniquet can be applied proximally to delay absorption.
TREATMENT
In anaphylaxis, adrenaline 0.5 to 1ml. is administered subcutaneously. It works as the most effective antidote; in extreme urgency. A tourniquet should, if possible, be applied proximal to the injection site to delay absorption. The patient is placed in a recumbent position and if necessary, oxygen maybe given with a bronchodilator through intermittent positive pressure breathing. Injection of antihistamine and intravenous cortisone can be helpful.
Desensitization with penicillin is too hazardous in patients with a histroy of an immediate or anaphylactic reaction.
Those who are allergic to penicillin or its derivatives may also be allergic to related drugs like ampicillin and amoxycillin.
ALLERGY TO ASPIRIN
The commonly used and innocuous looking aspirin is one of the regular offenders as far as allergic drug reactions are concerned. While most people who take the usual dose of aspirin suffer no immediate ill effects, there are some who are allergic to it and they suffer from a variety of adverse reactions. Skin rashes or urticaria over the whole body or over the eyelid, lips and face are known to occur after takng aspirin. Swelling of the tongue, throat and larynx is sometimes so severe that it leads to suffocation.
Much more serious, however, is the onset of asthma in susceptible persons, after repeated doses of aspirin. Upto 20 percent of severly ill, adult asthma patients have been found to have aspirin allergy. Some of these patients are unaware of this until an asthma attack is experimentally provoked in them by giving them test doses of aspirin.
Some of the characteristic features of asthma due to aspirin allergy are—persons with aspirin allergy may develop asthma upto three hours after taking the drug, because of this latent period, many patients fail to connect the taking of aspirin with the subsequent attack. Even after the patient stops taking aspirin, the asthma attacks usually continue. This occurs more frequently in adults than in children.
Many patients, have nasal polyps. Several asthma patients allergic to aspirin, show positive skin reactions to other allergens as well such as, pollens and dusts. Skin tests with aspirin are generally negatives; it is only the case history of the experimental trial that helps in the diagnosis of allergy to aspirin.
These patients must be warned of the presence of aspirin in many of the pain-killing and fever relieving tablets and mixtures.