Generally, Iran does not pose any particular health problems and no vaccinations are required. As a precautionary measure, it is recommended that you update your vaccination against tetanus, poliomyelitis, typhoid, hepatitis B and diphtheria before travelling. The standards of hygiene are high and most travellers will not experience any problems in the summer, apart perhaps from fatigue due to the heat.
However, it is better to bring with you medications to treat stomach discomfort, a few dressings, a disinfectant, aspirin, good sunscreen, and any special medications you may need. Tap water is drinkable almost everywhere in the country. However, it is recommended to drink bottled mineral water.
If you take specific medications, be careful to put the necessary medication in your hand luggage for the duration of your trip to avoid any problem in case of loss or late delivery of your luggage.