Hi guys,
I'm a Gp registrar in the UK
Benzamycin was discontinued in March 2007 with no obvious replacement. Duac is the obvious alternative using a similar macrolide (type of antibiotic).
I have found Benzoyl Peroxide an excellent treatment for acne as it is available in 2.5, 5 and 10%. As Quinoderm it is available cheap over the counter as 5 and 10%.
There is absolutely no reason why you cannot use the separate ingredients conatined in Benzamycin, however you need a prescription for the topical erythromycin (Zineryt).
I would use zineryt first then apply BP on top as this is a cream so doesn't absorb as well.
All types of skin are different and so react to products and combinations differently. If you experience mild burning, redness or soreness this often settles down after continued use. If you experience severe symptoms or an itchy rash then you should stop the product.
In answer to the question, the next option may be an alternative oral antibiotic such as oxytetracycline.