Why Do Bee Stings Hurt?

Date: 17th May 2021

Have you ever been stung by a bee?  If so, I’ll wager it hurt! But why do bee stings hurt?  

The short answer is:
In simple terms, there are two reasons that a bee sting causes pain and discomfort: 1. skin and tissue damage caused by the stinger piercing the skin; and 2. the effects of chemical components in bee venom, namely stimulation of pain nerves and histamine release. 

There is, of course an extra consideration for those who are severely allergic to bee venom.

Why bee stings hurt

The role of the stinger in pain from bee stings

Whilst it's true that a vaccine injection skillfully undertaken, will cause very little discomfort, if someone were to grab a pin or sewing needle and deliberately stick it into your arm in an ad hoc fashion, it would hurt.  In a sense, a bee stinger in the skin is a little like being pricked by a pin or sewing needle.  It's an ad hoc event, and a tiny wound from a sharp object that will cause immediate, if temporary pain.

When the bee’s stinger pierces the skin, it causes cell damage to both nervous and ‘non-nervous’ tissue. This damage causes stimulation of pain nerves (so we feel pain). 

Pain and discomfort are however, prolonged by the venom entering the skin via the stinger.

The role of venom in pain from bee stings

Bee venom has two main effects which contribute to pain and discomfort:

• the stimulation of pain nerves.
• the stimulation of histamine release, thus causing allergic affects, such as swelling and inflammation, itching.

When a bee stings a human, venom is injected into the skin at the site of the small, needle-sized wound. 

Principally, most of the insect venoms that sting humans are composed of peptides, proteins, enzymes and other smaller molecules. Bee venom consists of these molecules too, but the peptides melittin, apamin, and mast cell degranulating peptides are exclusive to bees.  These peptides are largely responsible for the discomfort caused by bees stings.

The following chemicals are some of the components found in ‘bee venom’ that contribute in some way to the unpleasant experience of being stung by a bee.  Some are directly responsible for the experience of discomfort, whilst others are facilitators, helping the toxins to take effect.

• Mellitin
  Mellitin is the main chemical component of bee venom responsible for pain.  It makes up about half (50-60%) of the dry weight of honey bee venom, and is the most toxic component.
  Mellitin causes pain and tissue destruction and stimulates pain nerves (called nociceptors) - so that we feel pain. 
  Mellitin also causes histamine release, thus stimulates the inflammation process, and is partly responsible for any severe allergic reaction experienced by some people.  
  
  
• Phospholipase A2
  This is the second most abundant compound in bee venom, accounting for around 10-12% of dried bee venom weight, and is the most allergenic factor.   It has been found that this component produces allergenic sensitization in 57-97% of the allergic patients.
  
  
• Apamin
  Apamin is a neurotoxic peptide.  It damages nerve cells, leading to the experience of pain.  Apamin accounts for about 2%–3% dry weight of bee venom.
  
  
• MCD peptide (mast cell degranulating peptide)
  This chemical is also responsible for triggering histamine release, thus causing allergic effects and inflammation response, which leads to swelling and pain.  MCD peptide accounts for about 1-3% dry weight of bee venom.
  


• Hyaluronidase
  This is another enzyme. It is thought that this enzyme is responsible for the process whereby the venom gets into cells. It accounts for about 1.5-2% dry weight of bee venom.

Anaphylaxis - extreme allergic reaction

For most people, treating bee stings is a relatively simple process to manage temporary discomfort.  However, in rare cases, for some people a bee sting can be fatal, or potentially fatal due to an extreme allergic reaction to bee venom - an anaphylactic reaction. 

Anaphylaxis is a very serious allergic response that has a rapid onset and which may lead to death. Symptoms of anaphylaxis in addition to normal reactions, could include swelling of the tongue and throat, shortness of breath, low blood pressure and collapse.  People who are aware they are at risk of serious allergic reaction, must carry an Epi-pen.  Untreated, anaphylaxis can be fatal.

Serious reactions to bee sting are not very common. Various studies and surveys reveal a wide range of figures, but measured mortality (death) rates varying from 0.3 per million people to 0.45 per million people (i.e. 1 person in 3.3 million people to 1 person in every 4.5 million people - far fewer than say, road traffic accident). 

Therapeutic uses of bee venom

Despite the toxic, allergenic and pain-inducing effects of bee venom, it is known to have a number of therapeutic effects when administered in appropriately and carefully controlled doses.  For example, it has bee found that mellitin can inhibit cell growth of human ovarian cancer cells.  MCD peptide at appropriate levels, is a potent anti-inflammatory agent.  These are just some of the known medicinal uses.

Wasp venom

As a quick extra point of interest, wasp venom is slightly different from bee venom. Some of the constituents are the same, such as phospholipase A; hyaluronidase and alarm pheromones. Wasp venom also contains phospholipase B (which plays a role in immobilising prey), wasp kinin (which causes inflammation), and acetylcholine (which stimulates pain nerves – thus causing the pain we experience from a wasp sting). Wasp venom does not contain mellitin.

Resources

• Gu, Hyemin et al. “Therapeutic Effects of Apamin as a Bee Venom Component for Non-Neoplastic Disease.” Toxins vol. 12,3 195. 19 Mar. 2020, doi:10.3390/toxins12030195
• Carpena M, Nuñez-Estevez B, Soria-Lopez A, Simal-Gandara J. Bee Venom: An Updating Review of Its Bioactive Molecules and Its Health Applications. Nutrients. 2020 Oct 31;12(11):3360. doi: 10.3390/nu12113360. PMID: 33142794; PMCID: PMC7693387. https://pubmed.ncbi.nlm.nih.gov/33142794/
  
• Annila I, Saarinen JV, Nieminen MM, Moilanen E, Hahtola P, Harvima IT. Bee venom induces high histamine or high leukotriene C4 release in skin of sensitized beekeepers. J Investig Allergol Clin Immunol. 2000 Jul-Aug;10(4):223-8. PMID: 11039839.
• Kasozi Keneth Iceland, Niedbała Gniewko, Alqarni Mohammed, Zirintunda Gerald, Ssempijja Fred, Musinguzi Simon Peter, Usman Ibe Michael, Matama Kevin, Hetta Helal F., Mbiydzenyuy Ngala Elvis, Batiha Gaber El-Saber, Beshbishy Amany Magdy, Welburn Susan Christina. Bee Venom—A Potential Complementary Medicine Candidate for SARS-CoV-2 Infections. Frontiers in Public Health. VOL.8 2020 : DOI=10.3389/fpubh.2020.594458 .