Are ‘Morning After’ Antibiotics an Answer to the Spread of Syphilis?

These days the word “antibiotics” tends to bring to mind another: “resistance”. As we’ve reported several times over the past year, antibiotic resistance is a growing problem. In the UK we’ve been hit with multiple cases of so-called “super gonorrhoea”, strains that have become untreatable after developing resistance to the antibiotics used to treat it.

In the same period, we’ve also seen a rather concerning increase in diagnoses of syphilis. Though the overall numbers don’t compare to big hitters like chlamydia (in 2016 there were 202,546 cases of chlamydia and 5,920 of syphilis), the rate at which cases are multiplying does suggest that, within a few years, we could have a serious problem on our hands. From 2015 to 2016, diagnoses of syphilis increased by 12%, and the number of reported cases was the highest it’s been since 1949.

The obvious explanation for this increase is that people today simply don’t have an awareness of the disease. It is not common knowledge, for instance, that the first symptom of syphilis infection is a small, painless sore or ulcer appearing on the genitals.

Because most people only develop one sore, and because they are usually painless, it can be easy to miss – and yet, these sores are the route of transmission for the infection. Having sex with someone who has a sore can lead to you contracting the disease – and if you aren’t aware that this was a risk, you may not end up getting checked for many months.

Another explanation for the spread is the widening availability of pre-exposure prophylaxis, which is taken to avoid contracting HIV; some people are concerned that the use of PrEP leads to a relaxed attitude towards unprotected sex (although no data has confirmed this trend yet).

Whatever the specific causes, the biggest question we should be asking at this point is how to stop the spread of syphilis. According to one recent study, the answer lies with “morning after” antibiotics.

Post-Exposure Antibiotics for Syphilis

The study linked to above was carried out by Dr Jean-Michel Molina, head of infectious diseases at Saint-Louis Hospital in Paris. It found that STI rates (and specifically rates of syphilis and chlamydia) fell dramatically in men who were given two tablets of the antibiotic doxycycline after episodes of unprotected sex.

The study was run over a period of around nine months, and looked at a total of 232 men who have sex with men (half of whom were put in the treatment group), with each man taking an average of 6.8 tablets per month. The final numbers showed a 73% fall in rates of syphilis and a 70% fall in rates of chlamydia.

The crucial information here is that the men were instructed to take doxycycline within 24 hours, and no later than 72 hours after unprotected sex (the same timeframe as the most common version of the morning after pill). It’s not entirely clear what the benefit of this short timeline is, but it mimics the post-exposure treatment administered for HIV.

Despite the seemingly positive effects gleaned from this study, Molina has garnered some criticism, with doctors warning that the use of doxycycline in this manner could contribute to antibiotic resistance.

It’s worth noting too that even Molina has his doubts; he has pointed out that the study length was too short to be definitive, and that such a programme should not be rolled out on a wide scale, but rather used for small groups over a short time.

Preventing the Spread of Syphilis

Whether or not Molina’s study is irresponsible given growing rates of antibiotic resistance, “morning after” antibiotics are unlikely to become a trend anytime soon. For men and women concerned about syphilis, the best thing to do is to practise safe sex and get regularly tested if you think you might be at risk.

If you’re sleeping with new or casual partners whose STI status is unclear, you should always use condoms and dental dams. If you spot any unusual symptoms in yourself or your partner, including any kinds of sores or ulcers on the genitals, refrain from sex and get tested.

You can get tested for syphilis at NHS centres, or through The STI Clinic. Click here to order our syphilis home test kit.