Are boar bristle brushes allowed for Muslim men?

Why boar bristle is a concern

Boar bristle is a popular, stiff natural hair used in beard brushes, hair brushes, shaving brushes and some toothbrushes. The Quran singles out the pig as impure:

Many scholars take "impure" (rijs) to mean the pig as a whole, not only its meat. That is why people avoid pigskin as well. See Can Muslims wear pigskin leather? For the reasons behind the prohibition, see Why can't Muslims eat pork?

What the schools say about hair

• Hanafi, Shafi'i and Hanbali: in general, pig hair is treated as impure, like other parts of the animal. Some Hanafi texts allowed cobblers to use pig bristle for stitching, out of need.
• Maliki: generally the most lenient on animal hair. Hair that has been shorn from the animal is considered pure, even from a pig.

So there is a real difference of opinion. Still, since brushes without pig bristle are cheap and common, most advice is simply to choose a different one.

What if I already have one?

You haven't sinned for something you used before you knew, or before you became Muslim. From here:

• Dry bristles touching dry hair don't spread impurity. If the brush is wet, or your hair or beard is wet, wash your hands and the area afterwards.
• Avoid using it when you plan to pray soon after, if your hair or the brush is wet.
• When it wears out, replace it with a boar-free brush. Selling it is discouraged, since pig products are generally not traded.

What to buy instead

• Synthetic bristles: nylon or similar. They're soft, cheap and easy to wash.
• Plant fibres: tampico (agave), coconut fibre or other vegetable bristles. These are common in "vegan" or "plant-based" brushes.
• Wooden combs: a good beard comb works well for most men and has no bristle issues.

Be careful with labels. "Natural bristle" often means boar. Look for "boar-free", "vegan" or "synthetic", or ask the seller. The same goes for beard and shaving brush kits, which may not state the hair clearly. For more about styling a beard, see Can Muslim men have a goatee or a styled beard?