After a few days out in the wild you may start to notice a strange odor that seems to follow you around. It's most likely not anything wrong with your environment or anything around it - it's probably you. Especially if you're travelling with others, a few days without any personal hygiene attention isn't just noticeable, it can also be very unhealthy. While 'clean' is always going to be relative in the outdoors it's still important to take care of yourself. Whether you're out on a weekend trip or a multi-day hike, basic hygiene should always be a consideration when packing for your journey.
Not only is maintaining your personal hygiene good for your general health, it's also a helpful way to rejuvenate yourself and boost your morale. That 'fresh clean' feeling can go a long way, especially if you have several more days and/or miles to cross before your trip is over. While it will be up to the individual to decide what they need the most, there are some basic items that everyone should carry. If you're going on a weekend camping trip and relying on your vehicle for most of your hauling needs, you can certainly carry things like a camp shower, pop up shower tent, and a variety of soaps (bio-degradable of course). If you're backpacking you have much less real estate, and weight, to use for hygiene products. This is where it's going to be more difficult to keep yourself clean, but also where it's going to be more important.
Since most organized camp sites that are frequented for weekend camping will have comforts such as public bathrooms and even showers, most of those campers will not need to worry about packing much with them. For backpackers, carrying a camp shower, and the several gallons of water needed for it, is not something that is feasible. In this case there are several ways to keep yourself clean, mixing supplies you may need to carry with you and what can be found within nature itself.
A toothbrush and small tube of toothpaste take up virtually no space in your pack, and should be in every pack for an extended trip. On top of that I also include a small box of floss. This can come in handy as cordage if need be, but I personally cannot stand having food stuck in my teeth that I cannot get rid of. Sticking my unkempt hands in there to fish it out is not only unhygienic, but is usually fruitless as well. While some of us may be alright with going several days without a body wash, making a habit of cleaning yourself regularly is also a good way to check your body for any irregularities. Especially if you're in a woodland environment, checking for parasites is an important part to maintaining your health. Physically scrubbing your body can reveal things your eyes may not have noticed.
When you decide you want to clean yourself is entirely up to you, but personally 3 days is my maximum before I'll do at least a basic wipe down. A few larger wet wipes work great to clean the accumulated sweat and grime from your skin, while cleaning any bacteria or microbes. A dip in a freshwater body is always great, but be aware that this may not be as clean as you may think. Sitting bodies of water have a higher chance of harboring bacteria, so if you intend to do this a flowing body of water is your best bet. Pay special attention to the parts of your body that don't get much sunlight, as that's where sweat will accumulate the most.
At least one pair of spare clothing is a great idea, and if you'll be out for several days you may want to consider more if your pack allows for it. While you can wear a T-Shirt or pair of pants for multiple days in a row, it's highly recommended to change your underwear and socks regularly. You can wear your underwear inside out at least once, and more if you choose, although this is not going to be the most hygienic practice. Keeping your socks dry is going to be important to preventing issues like trench foot. It may sound unlikely, but if you keep the same socks on for multi-day hike, the discomfort that begins can quickly worsen. Taking your socks off at night and hanging them to dry, if another pair is not available, is a great way to make sure your feet have a chance to dry off, as well as making sure your socks are dry before you begin the next days' hike. For those planning on extended trips you'll also want to bring items along to clean your clothing from time to time. A freshwater rinse is better than nothing, but using detergents and plastic bags - along with some elbow grease, you can replicate a washing machine spin and rinse cycle.
Moving away from full body cleaning, the most important thing to keep clean is going to be your hands. While some of us might be okay without a shower for a week, your hands certainly should get more attention than that. Since your hands are used for everything from going to the bathroom to cooking and then eating, making sure your hands are clean is extremely important to prevent yourself from getting sick. For this purpose, a small bottle of Hand Sanitizer should be found in every backpackers kit. Not only can this be used to clean your hands, it can also be used to disinfect other items, such as your eating utensils. Some brands of hand sanitizer are flammable as well, providing you a fast fire starter if needed.
As always, be sure to plan accordingly and never push yourself past your comfort zones. Make sure to bring extra food and water with you always, and stay safe and clean out there!