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Overview

In most cases, yes, you can safely take clindamycin if you have a known penicillin allergy.

Clindamycin and penicillin are in different medication classes and there is no known cross-sensitivity between them.[1]

In fact, many sources recommend clindamycin as a potential alternative antibiotic in those that are allergic to penicillin (depending on what you are treating).[2]


Penicillin Allergies

In terms of antibiotic allergies, penicillin-type antibiotics are the most common class in which people have documented allergies. Many studies report that up to 10% of individuals are allergic to them.[3]

In many cases, you'll hear the term 'beta-lactam allergy' substituted for 'penicillin-allergy'. 'Beta-lactam' antibiotics contain a 'beta-lactam' ring, an important component of the overall molecular structure of the compound.

Not only does penicillin contain a 'beta-lactam' ring, but many other antibiotics do as well, including:

  • Aminopenicillins (e.g. amoxicillin)
  • Cephalosporins (e.g. cephalexin)
  • Carbapenems (e.g. imipenem)

Overall, allergies to beta-lactam antibiotics are the most common:

"Allergic reactions to beta-lactam antibiotics are the most common cause of drug allergies in most epidemiological studies on adverse drug reactions."

If you are allergic to penicillin, there is a greater risk that you will be allergic to another class of drugs that also contain a beta-lactam ring (e.g. any of the drugs in the list above).[4]

Below are the chemical structures of two 'beta-lactam' antibiotics, penicillin and cephalexin. You can see they both are similar in structure and both contain a beta-lactam ring.

Penicillin Molecular Structure With Beta Lactam Ring Highlighted


Cephalexin With Beta Lactam Ring Highlighted

Since beta-lactam antibiotics are so similar in structure (and both contain the beta-lactam ring), it makes sense there would be a risk of allergic cross-reactivity between them. However, the exact risk of being allergic to more than one isn't well known.

Some sources report that there is nearly a 10% risk of being allergic to a cephalosporin drug if you have a known penicillin allergy. Other sources report the risk being much lower (closer to 1-2%).[5]

Nevertheless, it is pretty much agreed that there is some increased risk between most 'beta-lactam' antibiotics.


Clindamycin Allergies

Documented allergies to clindamycin are relatively rare. One study states this regarding it:

"Clindamycin may be associated with both immediate and non-immediate allergic reactions. However, the prevalence of such reactions is rare."

Serious adverse reactions, in general, with clindamycin are thought to be rare as well, occurring at rates less than 1%.[6]


Cross-Reactivity?

It isn't thought that there is an increased risk of being allergic to clindamycin if you have a known penicillin allergy. In other words, there isn't thought to be any cross-reactivity.

You can see from the molecular structure of clindamycin that it is not similar to penicillin and does not contain a beta-lactam ring.

Clindamycin Molecular Structure

One large review study concerning the therapeutic uses of clindamycin even states that the drug is a good alternative to penicillin in certain situations:

"...in the evidence-based publication Drugs of Choice, recommended topical clindamycin for moderate to severe acne vulgaris, and oral clindamycin as an alternative to the penicillins and cephalosporins for cellulitis and furunculosis in patients with drug allergies."

Final Words

It is natural to worry about potentially having allergies to other medications if you have a penicillin allergy.

Fortunately, not only is cross-reactivity among antibiotics similar to penicillin (e.g. cephalosporins) not thought to be all that common, there are many other classes of antibiotics available (e.g. clindamycin) with no known problems with cross-reactivity.

As always, be sure to discuss your concerns with your doctor to find the best course of therapy for your particular medical situation.


Summary

There is no known cross-reactivity between penicillin-type antibiotics (i.e. beta-lactam antibiotics) and clindamycin.

References
  1. ^ Update on the Management of Antibiotic Allergy. PubMed
  2. ^ Current indications for the use of clindamycin: A critical review. PubMed
  3. ^ The Three C’s of Antibiotic Allergy – Classification, Cross-Reactivity and Collaboration. PubMed
  4. ^ Hypersensitivity reactions to non beta-lactam antimicrobial agents, a statement of the WAO special committee on drug allergy. PubMed
  5. ^ THE FACTS ABOUT PENICILLIN ALLERGY: A REVIEW. PubMed
  6. ^ Update on clindamycin in the management of bacterial, fungal and protozoal infections. PubMed