How can I get ridoff cough?

I have been coughing for the past 4 weeks now. Its a tickly, dry-ish kind of cough. Went to see a Gp in one of the nhs walkin centres and was told that its a viral, not infection, therefore no medicines!! I have tried 3 different syrups including Veno, Benylin and honey and gargles etc etc.